home Calculators Gill apparatus and its derivatives. Development of the oral cavity. gill apparatus and its derivatives

Gill apparatus and its derivatives. Development of the oral cavity. gill apparatus and its derivatives

The development of the oral cavity, associated with the formation of the face, occurs as a result of the interaction of a number of embryonic rudiments and structures.

At the 3rd week of embryogenesis, at the cephalic and caudal ends of the body of the human embryo, as a result of invagination of the skin epithelium, 2 pits are formed - the oral and the cloacal. Oral pit or bay (stomadeum), represents the rudiment of the primary oral cavity, as well as the nasal cavity. The bottom of this fossa, in contact with the endoderm of the foregut, forms the oropharyngeal membrane (pharyngeal or oral membrane), which soon breaks through,

Rice. 1. The oral fossa (stomadeum) is separated from the primary intestine

pharyngeal membrane): 1 - oral fossa; 2 - pharyngeal membrane; 3 - forebrain; 4 - foregut; 5 - heart

in this case, a communication occurs between the cavity of the oral fossa and the cavity of the primary intestine (Fig. 1).

In the development of the oral cavity important role plays gill apparatus, which consists of 4 pairs of gill pouches and the same number of gill arches and slits (V pair is a rudimentary formation).

Gill pouches represent a protrusion of the endoderm in the pharyngeal region of the foregut.

Gill slits- invaginations of the cutaneous ectoderm cervical region, growing towards the projections of the endoderm.

The places where both meet are called gill membranes. In humans they do not break through.

Areas of mesenchyme located between adjacent pockets and crevices grow and form roller-like elevations on the anterior surface of the embryo's neck - gill arches(Fig. 2). The mesenchyme of the branchial arches has a dual origin: the central part of each arch consists of mesenchyme of mesodermal origin; it is surrounded by ectomesenchyme, resulting from the migration of neural crest cells.

Rice. 2. Gill arches in a longitudinal section: 1-4 - gill arches; 5 - gill arteries; 6 - stomadeum; 7 - remains of the pharyngeal membrane; 8 - pericardium; 9 - heart (according to Falin L.I., 1976, as amended)

The gill arches are covered on the outside with cutaneous ectoderm, and on the inside are lined with the epithelium of the primary pharynx. Subsequently, an artery, nerve, cartilage and muscle tissue are formed in each arch.

The first gill arch - the mandibular - is the largest, from which the rudiments of the upper and lower jaws are formed. From the second arch - the hyoid - the hyoid bone is formed. The third arch is involved in the formation of the thyroid cartilage.

Subsequently, the first gill slit turns into an external ear canal. From the first pair of gill pouches the cavities of the middle ear and eustachian tube arise. The second pair of gill pouches is involved in the formation of the palatine tonsils. From the III and IV pairs of gill pouches, the anlage of the parathyroid glands and thymus is formed. In the region of the ventral sections of the first 3 gill arches, the rudiments of the tongue and thyroid gland appear (see table).

Gill apparatus and its derivatives

With the development of the oral cavity, the first branchial arch is divided into 2 parts - the maxillary and mandibular. At first, these arcs in front are not combined into a single bookmark.

At the end of the 1st - beginning of the 2nd month of embryogenesis, the entrance to the oral fossa looks like a gap limited by 5 ridges, or processes. The unpaired frontal process is located superiorly (processus frontalis), on the sides the opening is limited by paired maxillary processes (processus maxillaris). The lower edge of the oral opening is limited by paired mandibular processes (processus mandibulares), which, merging along midline into a single arcuate mandibular process, forming the anlage for the lower jaw.

In the anterolateral parts of the frontal process, depressions are formed, surrounded by ridges - the nasal olfactory pits. The eye pads are located laterally. Nasal processes form in the middle part of the frontal process (rocessus nasalis) And nasal septum. The nasal pits gradually deepen, and their blind ends reach the roof of the primary oral cavity. At this point, a thin septum is formed, which then breaks through, giving rise to 2 openings - the primary choanae.

The primary palate is horseshoe-shaped and separates the nasal passages (primary nasal cavity) from the oral cavity. Subsequently, the anterior (proximal) part of the final palate is formed from it.

Simultaneously with the formation of the primary choanae, fast growth maxillary processes, they come closer to each other and to the medial nasal processes. As a result of these processes, a bookmark is formed upper jaw and upper lip.

The mandibular processes also fuse together along the midline and give rise to the formation of the lower jaw and lower lip.

Division of the primary oral cavity into the final oral cavity and nasal cavity associated with the formation of lamellar projections on the internal surfaces of the maxillary processes - palatine processes (Fig. 3).

At the end of the 2nd month, the edges of the palatine processes grow together. In this case, most of the palate is formed. The anterior part of the palate arises when the palatine processes fuse with the anlage of the upper jaw. The septum that arises as a result of these processes is the rudiment of a hard and soft palate. The septum separates the terminal oral cavity from the nasal cavity.

After the fusion of the palatine processes and the formation of the palate, the primary choanae no longer open into the oral cavity, but into the nasal chambers. The chambers communicate with the nasopharynx through the final definitive choanae.

Disruption of morphogenetic processes during embryogenesis can lead to various developmental defects. The most common of them is the formation of lateral clefts of the upper lip. (They are located along the line of fusion of the maxillary process with the medial nasal process.) Median clefts of the upper lip and upper jaw are much less common. (They are located in the place where the embryo’s medial nasal processes fuse with each other.) When the palatine processes are underdeveloped, their edges do not come close and do not fuse with each other. In these cases, the child develops a congenital malformation - a cleft of the hard and soft palate.

Rice. 3. Development of the palate and separation of the oral cavity

from the nasal cavity: a - embryo at the 6th week of development; b - embryo at the 8th week of development; 1 - nasal septum; 2 - language; 3 - palatine process; 4 - Meckel's cartilage (according to Bykov V.L., 1999, as amended)

2. GENERAL MORPHOFUNCTIONAL CHARACTERISTICS OF THE ORAL MUCOSA. TYPES OF MUCOSA

Oral cavity (cavitas oris) limited above by the hard and soft palate, below by the tongue and muscles of the floor of the mouth, in front and on the sides by the lips and cheeks (Fig. 4). In front it opens with the oral fissure (rima oris), which is limited by the lips (labia). Through the pharynx (fauces) the oral cavity communicates with the pharynx.

The alveolar processes of the jaws and teeth divide the oral cavity into 2 sections: the vestibule of the mouth (vestibulum oris) and the oral cavity itself (cavitas oris propria).

The vestibule of the mouth is an arched gap between the cheeks and gums with teeth. The oral cavity itself is limited in front and on the sides by the teeth, on top by the palate, and below by the bottom of the oral cavity.

The oral cavity with all its structural components is the beginning of the digestive system.

The oral mucosa is formed by stratified squamous epithelium, located on the basement membrane, and the lamina propria, which is formed by loose fibrous connective tissue. The lamina propria of the mucous membrane passes into the submucosa without a sharp boundary. (The muscular plate of the mucous membrane, characteristic of the mucous membrane of the digestive canal, is absent in the oral cavity.)

Visually, the surface of the oral mucosa is flat and smooth over a large area. The hard palate has transverse folds. There may be small yellowish spots on the lips and cheeks.

cottony elevations are Fordyce spots. These are the excretory ducts of the sebaceous glands, which open onto the surface of the mucous membrane. They are a product of the secretion of ectopically located sebaceous glands, which are usually located in the skin near hair follicles. Fordyce spots are more often found in the oral cavity of older people. They are rare in children and adolescence. On the mucous membrane of the cheek along the washing line

Rice. 4. Oral cavity: 1 - hard palate; 2 - soft palate; 3 - palatal suture; 4 - tongue; 5 - palatine tonsil; 6 - back of the tongue (according to Sinelnikov R.D., 1966, as amended)

The tooth decay (white line) is an area of increased keratinization. There are papillae on the dorsal surface of the tongue.

The oral mucosa performs a variety of functions, the main of which are protective (barrier), sensory, immunological control, food tasting, etc. The epithelium of the mucous membrane protects the underlying tissues from the damaging effects of mechanical, chemical, and thermal factors.

The lingual tonsil, part of the lymphoepithelial pharyngeal ring, is one of the components of the body's immune system.

Sensory function is associated with the presence in the oral mucosa of receptors that perceive tactile, temperature and pain stimuli.

Taste buds, located on the dorsal surface of the tongue, are the peripheral part of the taste analyzer.

The thin mucous membrane in the area of the floor of the oral cavity is easily permeable to a number of substances, so some medications It is recommended to place it under the tongue.

Based on the morphofunctional features in the oral cavity, it is customary to distinguish 3 type of mucosa: chewing (tunica mucosa masticatoria), lining (tunica mucosa vestiens) and specialized. The chewing mucosa lines the hard palate and gums. The lining (integumentary) mucous membrane is characteristic of the cheek, lip, floor of the mouth, alveolar processes, the anterior surface of the soft palate and the lower (ventral) surface of the tongue. A specialized mucous membrane covers the upper (dorsal) surface of the tongue.

The initial section of the foregut is the site of formation of the gill apparatus, consisting of five pairs of gill pouches and the same number of gill arches and slits, which take an active part in the development of the oral cavity and face, as well as a number of other organs of the embryo.

The first to appear are the gill pouches, which are protrusions of the endoderm in the area of the lateral walls of the pharyngeal or gill portion of the primary intestine. The last, fifth, pair of gill pouches is a rudimentary formation. Invaginations of the ectoderm of the cervical region, called gill slits, grow towards these protrusions of the endoderm. Where the bottom of the gill slits and pouches touch each other, gill membranes are formed, covered on the outside with dermal epithelium and on the inside with endodermal epithelium. In the human embryo, a breakthrough of these gill membranes and the formation of true gill slits, characteristic of lower vertebrates (fish, amphibians), does not occur.

Areas of mesenchyme located between adjacent gill pouches and slits grow and form on the anterolateral surface of the neck

the embryo has roller-like elevations. These are the so-called gill arches, which are separated from each other by gill slits. Myoblasts from myotomes join the mesenchyme of the gill arches and they participate in the formation of the following structures: I gill arch, called the mandibular arch, participates in the formation of the rudiments of the lower and upper jaw, masticatory muscles, and tongue; II arch – hyoid, participates in the formation of the hyoid bone, facial muscles, tongue; III arch – pharyngeal, forms the pharyngeal muscles, participates in the formation of the tongue; IV-V arches - laryngeal, forms cartilages and muscles of the larynx.

The first gill cleft develops into the external auditory canal, and the auricle develops from the fold of skin surrounding the external auditory opening.

Concerning gill pockets and their derivatives, then:

- from the first their pairs arise middle ear cavity and eustachian tubes;

- from the second pair of gills pockets are formed by the palatine tonsils;

- from the third and fourth pair- rudiments of the parathyroid glands and thymus gland.

Defects and developmental anomalies may occur in the area of gill pouches and slits. If the process of reverse development (reduction) of these structures is disrupted, blind cysts, cysts with access to the skin surface or into the pharynx, and fistulas connecting the pharynx with the outer surface of the skin of the neck can form in the cervical region.

Language development

Language laying occurs in the area of the first three gill arches. In this case, the epithelium and glands are formed from ectoderm, connective tissue - from mesenchyme, and skeletal muscle tongue - from myoblasts migrating from the myotomes of the occipital region.

At the end of the 4th week, three elevations appear on the oral surface of the first (maxillary) arch: in the middle unpaired tubercle and on the sides two side bolsters. They increase in size and merge together to form tip and body of tongue. Somewhat later from the thickenings on the second and partly on the third gill arches develops root of tongue with epiglottis. The fusion of the root of the tongue with the rest of the tongue occurs in the second month.

Congenital tongue defects are very rare. Isolated cases have been described in the literature underdevelopment (aplasia) or lack of language (aglossia), splitting it, double tongue, lack of frenulum of the tongue. Most common forms of anomalies are enlarged tongue (macroglossia) and shortening of the frenulum language. The reason for the enlargement of the tongue is the excessive development of its muscle tissue or diffuse lymphangioma. Anomalies of the frenulum of the tongue are expressed in an increase in the length of its attachment towards the tip of the tongue, which limits its mobility; Congenital defects also include non-closure of the blind foramen of the tongue.

Dental malformations primarily include anomalies associated with impaired development of teeth (deciduous and permanent) both in the embryonic and post-embryonic periods. There are various reasons behind such anomalies. Developmental defects include anomalies in the arrangement of teeth in the jaw, anomalies with a violation of the normal number of teeth (decrease or increase), anomalies in the shape of teeth, their size, fusion and fusion of teeth, anomalies in teething, anomalies in the relationship of the dentition when they are closed. Anomalies in the location of teeth - on the hard palate, in the nasal cavity, reversal of the canine and incisor. In addition, structural defects of hard tissues (both milk and permanent) include changes in enamel, dentin, and cement.

(IX pair of cranial nerves);
derivatives IV - superior laryngeal branch of the vagus nerve (X pair of cranial nerves);
derivatives V - inferior laryngeal branch vagus nerve

Gills or visceral arcs(lat. Árcus branchiales seu árcus visceráles ) - paired arcuate cartilaginous plates of the gill skeleton of lower vertebrates and embryos of higher vertebrates, including primates and humans, part of the visceral skeleton of vertebrates, bone or cartilaginous formations developing in the wall of the pharynx between the pharyngeal pouches. Fish have from 3 to 7 gill arches, each of which is divided into four movably connected sections and is located between the gill slits; gills develop on the outer surface of the gill arch. In terrestrial vertebrates, the branchial arches transform during embryonic development: the upper segments are reduced, and the lower ones participate in the formation of the hyoid apparatus and turn into cartilage of the larynx and trachea.

Anatomy

Fish

Gill arches are a system of skeletal elements of the pharynx in cyclostomes and fish, each of which covers the pharynx in a semi-ring. Most modern fish have five gill arches, while cyclostomes and some sharks have up to seven. Due to the reduction of the distal ones (located closer to the tail), the number of gill arches in bony fish can be reduced to three. According to the anatomical structure, the gill arches of cyclostomes, cartilaginous, sturgeon and lungfishes are cartilaginous, while those of bony fish are bony. Fully formed gill arches of fish consist of 4 movably connected segments. In bony fishes, the fifth gill arch, called the lower pharyngeal bone, is usually rudimentary, but in cyprinids it bears teeth and can be quite massive.

Embryology

Fish

As the brain develops in fish, a protective box forms around it:

in cartilaginous (shark) fish - cartilaginous - acquires cartilaginous tissue and forms a cartilaginous skull,
in bony fish - the bony fish - the bony skull begins to form.

Amphibians

Reptiles

In more developed classes of vertebrates, connective and cartilaginous tissue is completely replaced by bone tissue - a more durable bone skull is formed. Thus, in terrestrial vertebrates, the number of bones decreases, and their structure becomes more complex, since a number of bones are the result of fusion of previously independent bone formations.

Birds

Mammals

In mammals (or animals), the visceral and cerebral skulls are closely fused together.

Homo sapiens

connective tissue,
cartilaginous,
bone.

Moreover, the transition from the second stage to the third (the formation of secondary bones in place of cartilage) occurs throughout a person’s entire life. Thus, even an adult person retains synchondrosis(cartilaginous joints) - remnants of cartilaginous tissue between bones.

Derivatives of gill arch cartilage:

I - from the upper part of the first gill (or maxillary) arcs (lat. Processus maxillaris) the upper jaw is formed, on the ventral (facing the abdomen) cartilage (lat. Processus mandibularis) is formed lower jaw, articulating with the temporal bone through the temporomandibular joint. The remaining parts of the cartilage of the first branchial arch turn into auditory ossicles: malleus and incus.

II - upper section of the second gill ( sublingual or hyoid) arch gives rise to the third auditory ossicle - the stapes. Thus, all three auditory ossicles are not related to the bones of the facial skull and are located in the tympanic cavity, which is part of the middle ear and develops from the first gill pouch. The rest of the hyoid gill arch is used to construct fragments of the hyoid bone: the small horns and part of its body, as well as the styloid processes of the temporal bone and the stylohyoid ligament (lat. Ligamentum stylohyoideum).

III - the third branchial arch serves as a source for the remaining part of the body of the hyoid bone and forms its large horns.

IV-V (VII) - the remaining gill arches serve as a source for the thyroid and other cartilages of the larynx and trachea.

motionless - upper jaw, palatine and zygomatic bones;
movable - lower jaw, hyoid bone and auditory ossicles.

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Notes

Human anatomy / Prives M. G., Lysenkov N. K. - 9th ed., revised. and additional - M.: Medicine, 1985. - P. 87-89. - 672 s. - ( Educational literature for students of medical institutes). - 110,000 copies.
Human anatomy in two volumes / Ed. acad. RAMS prof. M. R. Sapina. - 5th ed., revised. and additional - M.: Medicine, 2001. - T. I. - P. 169-173. - 640 s. - (For medical students, graduate students, doctors). - ISBN 5-225-04585-5.
Paul R. Ehrlich., David S. Dobkin, Darryl Wheye. . Birds of Stanford. Stanford University (1988). Retrieved December 13, 2007. . based on The Birder's Handbook (Paul Ehrlich, David Dobkin, and Darryl Wheye. 1988. Simon and Schuster, New York.)
Frank Gill. Ornithology = Ornithology. - New York: WH Freeman and Co, 1995. - 720 p. - ISBN 0-7167-2415-4.
V.D. Ilyichev, N.N. Kartashev, I.A. Shilov. General ornithology. - M.: Higher School, 1982. - 464 p.

Literature

Biological encyclopedic Dictionary/ Ch. ed. M. S. Gilyarov; Editorial team: A. A. Baev, G. G. Vinberg, G. A. Zavarzin and others - M.: Sov. encyclopedia, 1986. - P. 831. - 100,000 copies.
Severtsov A. N. Morphology of the visceral apparatus of elasmobranchia, Collection of works, vol. 4, M. - L., 1948.
Himmelreich G. A. Visceral apparatus of sturgeons as an organ of food intake, in the book: Issues of evolutionary morphology of vertebrates, M., 1963.

An excerpt characterizing the Gill arches

Prince Andrei ordered to stop and asked the soldier in what case they were wounded. “The day before yesterday on the Danube,” answered the soldier. Prince Andrei took out his wallet and gave the soldier three gold coins.
“For everyone,” he added, turning to the approaching officer. “Get well, guys,” he addressed the soldiers, “there’s still a lot to do.”
- What, Mr. Adjutant, what news? – the officer asked, apparently wanting to talk.
- Good ones! “Forward,” he shouted to the driver and galloped on.
It was already completely dark when Prince Andrei entered Brunn and saw himself surrounded by tall buildings, the lights of shops, house windows and lanterns, beautiful carriages rustling along the pavement and all that atmosphere of a large, lively city, which is always so attractive to a military man after the camp. Prince Andrey, despite driving fast and sleepless night Approaching the palace, I felt even more animated than the day before. Only the eyes sparkled with a feverish brilliance, and thoughts changed with extreme speed and clarity. All the details of the battle were vividly presented to him again, no longer vaguely, but definitely, in a condensed presentation, which he made in his imagination to Emperor Franz. He vividly imagined random questions that could be asked of him, and the answers that he would make to them. He believed that he would immediately be presented to the emperor. But at the large entrance of the palace an official ran out to him and, recognizing him as a courier, escorted him to another entrance.
- From the corridor to the right; there, Euer Hochgeboren, [Your Highness,] you will find the adjutant on duty in the wing,” the official told him. - He takes you to the Minister of War.
The adjutant on duty in the wing, who met Prince Andrei, asked him to wait and went to the Minister of War. Five minutes later, the aide-de-camp returned and, bending especially politely and letting Prince Andrei go ahead of him, led him through the corridor into the office where the Minister of War was working. The aide-de-camp, with his exquisite politeness, seemed to want to protect himself from the Russian adjutant’s attempts at familiarity. Prince Andrei's joyful feeling weakened significantly when he approached the door of the War Minister's office. He felt insulted, and the feeling of insult at that same moment, unnoticed by him, turned into a feeling of contempt, based on nothing. His resourceful mind at the same moment suggested to him the point of view from which he had the right to despise both the adjutant and the minister of war. “They must find it very easy to win victories without smelling gunpowder!” he thought. His eyes narrowed contemptuously; He entered the office of the Minister of War especially slowly. This feeling intensified even more when he saw the Minister of War sitting over a large table and for the first two minutes did not pay attention to the newcomer. The Minister of War lowered his bald head with gray temples between two wax candles and read, marking with a pencil, the papers. He finished reading without raising his head, when the door opened and footsteps were heard.
“Take this and hand it over,” the Minister of War said to his adjutant, handing over the papers and not yet paying attention to the courier.
Prince Andrei felt that either of all the affairs that occupied the Minister of War, the actions of Kutuzov’s army could least of all interest him, or it was necessary to let the Russian courier feel this. “But I don’t care at all,” he thought. The Minister of War moved the rest of the papers, aligned their edges with the edges and raised his head. He had a smart and characteristic head. But at the same moment as he turned to Prince Andrei, the intelligent and firm expression on the face of the Minister of War, apparently habitually and consciously changed: the stupid, feigned, not hiding his pretense, smile of a man who receives many petitioners one after another stopped on his face .
– From General Field Marshal Kutuzov? - he asked. - Good news, I hope? Was there a collision with Mortier? Victory? It's time!
He took the dispatch, which was addressed to him, and began to read it with a sad expression.
- Oh my god! My God! Shmit! - he said in German. - What a misfortune, what a misfortune!
Having run through the dispatch, he put it on the table and looked at Prince Andrei, apparently thinking about something.
- Oh, what a misfortune! The matter, you say, is decisive? Mortier was not taken, however. (He thought.) I am very glad that you brought good news, although the death of Shmit is an expensive price to pay for victory. His Majesty will probably wish to see you, but not today. Thank you, take a rest. Tomorrow be on the way out after the parade. However, I'll let you know.
The stupid smile that had disappeared during the conversation reappeared on the face of the Minister of War.
- Goodbye, thank you very much. The Emperor will probably wish to see you,” he repeated and bowed his head.
When Prince Andrei left the palace, he felt that all the interest and happiness brought to him by the victory had now been abandoned by him and transferred to the indifferent hands of the Minister of War and the courteous adjutant. His whole mindset instantly changed: the battle seemed to him like an old, distant memory.

Prince Andrei stayed in Brünn with his friend, the Russian diplomat Bilibin.
“Ah, dear prince, there is no nicer guest,” said Bilibin, going out to meet Prince Andrei. - Franz, the prince’s things are in my bedroom! - he turned to the servant who was seeing Bolkonsky off. - What, a harbinger of victory? Wonderful. And I’m sitting sick, as you can see.
Prince Andrei, having washed and dressed, went out to the diplomat’s luxurious office and sat down to the prepared dinner. Bilibin calmly sat down by the fireplace.
Prince Andrei, not only after his journey, but also after the entire campaign, during which he was deprived of all the comforts of cleanliness and grace of life, experienced a pleasant feeling of relaxation among those luxurious living conditions to which he had become accustomed since childhood. In addition, after the Austrian reception, he was pleased to talk, at least not in Russian (they spoke French), but with a Russian person who, he assumed, shared the general Russian disgust (now especially vividly felt) for the Austrians.
Bilibin was a man of about thirty-five, single, in the same company as Prince Andrei. They knew each other back in St. Petersburg, but they became even closer on Prince Andrei’s last visit to Vienna together with Kutuzov. Just as Prince Andrei was a young man who promised to go far in the military field, so, and even more, did Bilibin promise in the diplomatic field. He was still a young man, but no longer a young diplomat, since he began serving at the age of sixteen, was in Paris, in Copenhagen, and now occupied a rather significant position in Vienna. Both the Chancellor and our envoy in Vienna knew him and valued him. He wasn't one of those people large quantity diplomats who are required to have only negative virtues, not do well-known things and speak French in order to be very good diplomats; he was one of those diplomats who love and know how to work, and, despite his laziness, he sometimes spent the night at his desk. He worked equally well, no matter what the nature of the work was. He was not interested in the question “why?”, but in the question “how?”. What the diplomatic matter was, he didn’t care; but to draw up a circular, memorandum or report skillfully, accurately and gracefully - he found great pleasure in this. Bilibin's merits were valued, in addition to his written works, also by his art of addressing and speaking in higher spheres.
Bilibin loved conversation just as he loved work, only when the conversation could be elegantly witty. In society, he constantly waited for an opportunity to say something remarkable and entered into conversation only under these conditions. Bilibin's conversation was constantly peppered with original witty, complete phrases of general interest.
These phrases were produced in Bilibin’s internal laboratory, as if on purpose, of a portable nature, so that insignificant secular people could conveniently remember them and transfer them from living rooms to living rooms. And indeed, les mots de Bilibine se colportaient dans les salons de Vienne, [Bilibin’s reviews were distributed throughout Viennese living rooms] and often had an influence on so-called important matters.
His thin, emaciated, yellowish face was all covered with large wrinkles, which always seemed as cleanly and diligently washed, like fingertips after a bath. The movements of these wrinkles constituted the main play of his physiognomy. Now his forehead wrinkled in wide folds, his eyebrows rose upward, now his eyebrows went down, and large wrinkles formed on his cheeks. The deep-set, small eyes always looked straight and cheerful.
“Well, now tell us your exploits,” he said.
Bolkonsky, in the most modest way, without ever mentioning himself, told the story and the reception of the Minister of War.
“Ils m"ont recu avec ma nouvelle, comme un chien dans un jeu de quilles, [They accepted me with this news, as they accept a dog when it interferes with a game of skittles,] he concluded.
Bilibin grinned and loosened the folds of his skin.
“Cependant, mon cher,” he said, examining his nail from afar and picking up the skin above his left eye, “malgre la haute estime que je professe pour le Orthodox Russian army, j"avoue que votre victoire n"est pas des plus victorieuses. [However, my dear, with all due respect to the Orthodox Russian army, I believe that your victory is not the most brilliant.]
He continued in the same way in French, pronouncing in Russian only those words that he contemptuously wanted to emphasize.
- How? You with all your weight fell upon the unfortunate Mortier with one division, and this Mortier leaves between your hands? Where is the victory?
“However, seriously speaking,” answered Prince Andrei, “we can still say without boasting that this is a little better than Ulm...
- Why didn’t you take us one, at least one marshal?
– Because not everything is done as expected, and not as regularly as at the parade. We expected, as I told you, to reach the rear by seven o'clock in the morning, but did not arrive at five in the evening.
- Why didn’t you come at seven o’clock in the morning? “You should have come at seven o’clock in the morning,” Bilibin said smiling, “you should have come at seven o’clock in the morning.”
– Why didn’t you convince Bonaparte through diplomatic means that it was better for him to leave Genoa? – Prince Andrei said in the same tone.

Ticket 34.

Gill apparatus

Features of the structure of the gastric glands.

Cardiac glands of the stomach- a small group of glands, located in a limited area - in a zone 1.5 cm wide at the entrance of the esophagus to the stomach. The structure is simple, tubular, highly branched, and the nature of the secretion is predominantly mucous. By cellular composition mukocytes predominate, few parietal and main exocrinocytes, endocrinocytes.

Fundic (or own) glands of the stomach- the most numerous group of glands, located in the area of the body and fundus of the stomach. The structure is simple tubular, unbranched (or weakly branched) glands. The glands have the shape of straight tubes, located very tightly in relation to each other, with very thin layers of SDT. In terms of cellular composition, the main and parietal exocrinocytes predominate; the remaining 3 types of cells are present, but there are fewer of them. The secretion of these glands contains digestive enzymes of the stomach (see above), hydrochloric acid, hormones and hormone-like substances (see above), mucus.

Pyloric glands of the stomach– located in the pyloric part of the stomach, there are much fewer of them than fundic ones. The structure is simple, tubular, branched, and the nature of the secretion is predominantly mucous glands. They are located at a distance (less frequently) in relation to each other; between them there are well-defined layers of loose fibrous SDT. The cellular composition is dominated by mukocytes, a significant number of endocrine cells, very few or no main and parietal exocrinocytes.

There are 3 layers in the muscular lining of the stomach: internal - oblique direction, middle - circular direction, external - longitudinal direction of myocytes. The outer serous membrane of the stomach is without features.

Functions: The stomach is an important organ of the digestive system and performs the following functions:

1. Reservoir (accumulation of food mass).

2. Chemical (HCl) and enzymatic food processing (pesin, chemosin, lipase).

3. Sterilization of food mass (HCl).

4. Mechanical processing (dilution with mucus and mixing with gastric juice).

5. Absorption (water, salts, sugar, alcohol, etc.).

6. Endocrine (gastrin, serotonin, motilin, glucagon).

7. Excretory (release of ammonia from the blood into the stomach cavity, uric acid, urea, creatinine).

8. Production of an antianemic factor (Castle factor), without which the absorption of vitamin B12, necessary for normal hematopoiesis, becomes impossible.

Ticket number 35.

During its development, a tooth goes through 3 stages:

1. Formation and formation of tooth germs.

2. Differentiation of tooth germs. Early stages development.

3. Histogenesis of dental tissues (this is late stage)

During the first stage, the oral cavity is separated and its vestibule is formed. At the end of the 2nd month of intrauterine development, a buccal-labial plate is released from the epithelium of the oral cavity and grows into the mesenchyme. A gap is formed in this plate, separating the oral cavity and vestibule. An epithelial protrusion grows from the bottom of the vestibule, from which it forms dental plate. Along the free edge of the dental plate, as a result of the proliferation of the epithelium, flask-shaped protrusions or enamel buds (enamel caps) are formed. At the 10th week of embryonic development, mesenchyme, the dental papilla, begins to grow into each enamel cap from below. This cap turns into a double-walled cup – a dental/enamel organ.

The dental sac is formed from the mesenchyme surrounding the enamel organ.

The enamel organ, dental papilla and dental sac together form the tooth germ.

During the second stage of tooth development, fluid begins to accumulate between the cells of the central part of the enamel organ. As a result, the cells move away from each other, but remain connected by cytoplasmic bridges, thus forming the pulp of the enamel organ. The cells of the inner enamel epithelium become prismatic and then gradually turn into omeloblasts, the cells that form enamel. The cells of the outer enamel epithelium become flattened.

The third stage begins at the end of the 4th month of intrauterine development. Dentinoblast differentiation occurs. The basement membrane of omeloblasts is a differentiation factor. In the mesenchymal cells located underneath, the dental papilla reaches high development organelle synthesis. The cells begin to produce proteins of fibrous structures and turn into odontoblasts. The formation of fibers occurs outside the cells, the fibers are arranged radially. These fibers are called Corff fibers.

When the layer of predentin with Korff fibers reaches a certain size, it is pushed to the periphery by layers of dentin, in which the fibers run tangentially (Erb fibers).

Thus, mantle dentin is formed first, and then peripulpar dentin. The dental pulp develops from the dental papilla. The process of pulp differentiation occurs in parallel with the process of dentin development. The deposition of the first dentin layers induces the differentiation of omeloblasts. Synthesis organelles are developed in the cytoplasm of omeloblasts; the nuclei are shifted to the opposite pole of the cell. The first rudiments of enamel are formed in the form of cuticular plates on the surface of omeloblasts in the area of the tooth crown. Their calcification begins immediately as omeloblasts produce omelodenins - proteins that promote rapid mineralization of enamel.

Nutrition of omeloblasts after changing the poles of the cell is carried out from the pulp of the enamel organ, and not from the dentin. Gradually, the mistletoe blasts decrease in size and move away from the dentin.

In the mesenchyme of the dental sac, 2 layers are differentiated: outer and inner. From the inner layer in the area of the tooth root, cementoblasts differentiate, which produce cement. The periodontium differentiates from the mesenchyme of the outer layer.

Testicle: structure and functions.

Testicles, testicles (Latin testis, testiculus - “witnesses [of masculinity]”) - paired male gonads, in which male reproductive cells are formed - (spermatozoa) and steroid hormones, mainly testosterone.

Dimensions and position: the testicles are located in the scrotum and descend there from the retroperitoneum, usually at birth (the absence of a testicle in the scrotum occurs in 2-4% of full-term, 15-30% of premature newborns). This is necessary for normal sperm maturation, which requires temperature regime several tenths of a degree lower than the temperature in abdominal cavity.

Usually the testicles are located on at different levels and may differ in size - often the left one is lower and larger than the right one. The shape of the testicle resembles a slightly flattened ellipsoidal body, 3.5-5 cm long, 2.3-3.5 cm wide, weighing 15-25 g. In an adult healthy Caucasian male average volume testicles about 18 cm³, ranging from 12 cm³ to 30 cm³.

Structure: vas deferens, tunica vaginalis, head of epididymis, body of epididymis, upper end of testis,

lateral surface of the testicle, tail of the epididymis, anterior edge of the testicle, lower end of the testicle.

The testicles consist of individual lobules filled with convoluted seminal canals. The average length of the tubules is 50-80 mm. Total length - 300-400 mm. The tubules are surrounded by connective tissue septa, in which clusters of the so-called. interstitial cells (Leydig cells), secreting male sex hormones - androgens. In some diseases of men, sperm motility is absent or insufficient, which is one of the causes of male infertility. The outside of the testicles is covered with a serous membrane. On each testicle there is an epididymis on top, which passes into the vas deferens. The functions of the testicle are controlled by the anterior pituitary gland and hypothalamus.

Functions of the testicles: The convoluted tubules of the testicles produce male reproductive cells - sperm. The cells are produced from a specialized epithelium, with one cell of this epithelium producing four to eight sperm. In addition, male sex hormones are produced in the interstitial tissues of the testicle (glandulocytes).

Ticket number 36.

Formation of tooth germs.

First, in the area of the future anterior teeth, a dental plate originates from the vestibular plate at a right angle and grows into the underlying mesenchyme. During their growth, the epithelial dental plates take the form of two arches located in the mesenchyme of the upper and lower jaws.

Then, along the free edge of the plate on the anterior (buccal-labial) side, flask-shaped protrusions of the epithelium are formed (10 in each jaw) - tooth buds (gemmae dentis). At 9-10 weeks of embryonic development, mesenchyme begins to grow into them, giving rise to dental papillae (papillae dentis). As a result, the tooth bud takes the shape of a bell or bowl, transforming into epithelial dental organ (organum dentale epitheliale). Its inner surface, bordering the mesenchyme, bends in a peculiar way and the outlines of the dental papilla gradually take on the shape of the future tooth crown. By the end of the 3rd month of embryogenesis, the epithelial dental organ is connected to the dental plate only by a narrow epithelial cord - the neck of the dental organ.

Around the epithelial dental organ and under the base of the dental papilla, a thickening of mesenchyme is formed - dental sac (sacculus dentis).

Thus, in the formed dental germ, three parts can be distinguished: the epithelial dental organ, the mesenchymal dental papilla and the dental sac. This ends stage 1 of tooth development - the stage of formation of tooth germs, and the period of their differentiation begins.

Dental, papilla - This is the backbone of the dental pulp. The cells of the dental papilla multiply rapidly and soon form a very dense mass. The dental papilla appears around the tenth week of the baby's stay in the womb.

Dental sac. Formed during the embryonic stage of tooth development. Appears in the form of a compaction of mesenchyme covering the tooth germ.

Ticket number 37.

Ovary: structure and functions.

Ovaries - paired female reproductive glands located in the pelvic cavity. They perform a generative function, that is, they are the place where female germ cells develop and mature, and are also endocrine glands and produce sex hormones (endocrine function).

Structure: The ovaries consist of a stroma (connective tissue) and a cortex in which there are follicles in different stages of development (primordial, primary, secondary, tertiary follicles) and regression (atretic bodies, white bodies).

Functions: The ovaries produce steroid hormones. The ovarian follicular apparatus produces mainly estrogens, but also weak androgens and progestins. The corpus luteum of the ovaries (a temporary endocrine gland that exists only in the luteal phase of a woman’s cycle), on the contrary, produces mainly progestins, and to a lesser extent, estrogens and weak androgens.

A woman's ovaries work cyclically. During maturation, one of the follicles becomes dominant and inhibits the maturation of the others. The egg matures in the dominant follicle. When the follicle is fully mature, it bursts, and a second-order oocyte (egg is a more common term, but less correct) exits it into the abdominal cavity. This process is called ovulation. It is then captured by the fimbriae and the fluid flow created by peristalsis fallopian tube, enters the fallopian tube, through which it migrates to the uterus. If within 3 days (limitation is the lifespan of sperm) before ovulation and 1 day after ovulation (limitation is the lifespan of the egg), a woman had vaginal intercourse with a man, which led to the entry of a sufficient number of motile sperm into the vagina, then fertilization is likely oocyte of the second order (it occurs in the abdominal cavity or the lumen of the fallopian tube). If fertilization has taken place, then the embryo migrates.

The burst follicle undergoes transformation into the corpus luteum, which begins to secrete progestins. Then the corpus luteum undergoes resorption and reverse development, as a result of which the secretion of progestins drops sharply and menstruation occurs. After menstruation, the maturation of the follicles begins again, one of them becomes dominant - a new menstrual cycle begins.

Menstrual cycle in women it normally lasts on average 28 days (individual variations are possible, considered normal - from 25 to 31 days).

Throughout a woman's life, the ovary undergoes age-related changes like no other organ. The number of germ cells in the ovary of a female fetus at the 10th week of intrauterine development is about a million. This is their maximum number. Throughout the rest of life, the eggs gradually die, and by the age of 45 there are no more of them. The reproductive (childbearing) period for women is shorter than for men, lasting on average from 15 to 45 years. During this period, eggs mature cyclically, hormones are intensively produced, and pregnancy is possible. It is fundamentally important that new eggs in women (unlike sperm in men) do not appear, and only the existing ones are used up all the time. Thus, reproductive health a woman begins to form “in the womb”, the ovary “remembers” all the adverse effects, which can affect the ability to conceive and the quality of the offspring.

Ticket number 38.

1. Development of permanent teeth. Sources of development. Permanent replacement and permanent additional teeth.

Development of permanent teeth. Bookmarks for permanent teeth are formed both during intrauterine life (incisors, canines, first molars) and after birth. The eruption of permanent teeth occurs over a long period of time, from five to fifteen years, in the following order: (6, 1), (2, 4), (3, 5), 7. Wisdom teeth erupt only after 18 years.

According to statistics, also in permanent dentition lower teeth erupt earlier than the upper ones. A frequent exception is premolars. Closing of the root apex occurs 2-3 years after eruption. Until then, they talk about a tooth with incomplete development. The development of a permanent tooth continues for almost ten years. During the period of changing teeth, when milk and permanent teeth are temporarily in the oral cavity, they speak of a mixed bite.

Rudiments of permanent incisors- both upper and lower - are placed in the jaws in a wing-like manner. The fact is that their crowns are significantly larger in size than their predecessors, so that in small children’s jaws there is not enough space for them. Therefore, in the early age period, the echelon-like arrangement of the incisor rudiments is a completely normal phenomenon, and based on it one cannot make assumptions about a future anomaly. Along with the eruption of permanent teeth, the jaw grows in most cases so that there is sufficient space for the incisors in the future.

The beginnings of fangs They are always located relatively deep in the jaw, and there is also not enough space for them. However, here, too, normalization occurs with age, and therefore one should not rashly diagnose an impacted tooth.

Premolar rudiments They are located initially orally, and only in the subsequent period do they occupy a place between the roots of primary molars.

The beginnings of molars are noted in the early period of development, usually located in the ascending ramus of the lower jaw or in the tubercle of the upper jaw. With the developing growth of the jaws, the molar bud takes its permanent position. The only exception may be wisdom teeth, which erupt at a time when the growth of the jaws is almost complete, so the lack of space is persistent.

Development of teeth, formation and calcification of rudiments, migration of rudiments of permanent teeth towards the surface, resorption of the roots of milk teeth, eruption, etc. - all these are processes inextricably linked with general development body.

During life, 2 changes of teeth develop. The first change of teeth is called falling out or milk teeth and serves in childhood. There are 20 teeth falling out in total - 10 each in the upper and lower jaw. Falling out teeth function in in full force up to 6 years old. From 6 to 12 years of age, teeth that fall out are gradually replaced by permanent teeth. A set of permanent teeth consists of 32 teeth. The formula of the teeth is as follows: 1-2 – incisors, 3 – canine, 4-5 – premolars, 6-7-8 – molars.

Teeth are formed from 2 sources:

1. Oral epithelium – tooth enamel.

2. Mesenchyme - all other tooth tissues (dentin, cement, pulp, periodontium and periodontium).

At the 6th week of embryogenesis, the stratified squamous non-keratinizing epithelium on the upper and lower jaws thickens in the form of a horseshoe-shaped cord - the dental plate. This dental plate is subsequently immersed in the underlying mesenchyme. Epithelial protrusions appear on the anterior (labial) surface of the dental plate - the so-called dental buds. From the lower surface, compacted mesenchyme in the form of a dental papilla begins to be pressed into the dental bud. As a result of this, the epithelial tooth bud turns into an inverted 2-walled glass or thicket, which is called the epithelial enamel organ. The enamel organ and the dental papilla are together surrounded by compacted mesenchyme - the dental sac.

The epithelial enamel organ is first connected by a thin stalk to the dental plate. Cells of the epithelial enamel organ differentiate in 3 directions:

1. Internal cells (at the border with the dental papilla) - turn into enamel-forming cells - ameloblasts.

2. Intermediate cells - become processes, form a looped network - the pulp of the enamel organ. These cells participate in the nutrition of ameloblasts, play a certain role in teething, and subsequently flatten and form the cuticle.

3. Outer cells - flatten and degenerate after eruption.

Functionally, the most important cells of the enamel organ are the inner cells. These cells become highly prismatic and differentiate into ameloblasts.

Ticket number 39.

Ticket number 40.

Ticket number 41.

Ticket number 42.

1. Development of the dental plate and formation of dental germs, their differentiation.(see the first question of ticket No. 35).

Sources of development:

1. Endoderm of the pharyngeal intestine - epithelium of the ventral wall of the pharynx between the I and II pairs of gill pouches - tiracites.

2. Neural crest – parafollicular cells.

Composition and parameters of the thyroid gland:

The thyroid gland consists of two lobes and an isthmus. The lobes on the right and left are adjacent to the trachea, and the isthmus is located on its anterior surface. It happens that an additional pyramidal lobe extends from one of the lobes (usually the left one) or the isthmus.

Thyroid- the largest in endocrine system. Its right lobe is larger than the left and more abundantly vascularized.

Normal weight thyroid gland varies from 20 to 60 grams. The sizes of the lobes are 5-8, 2-4 and 1-3 cm. During puberty, the mass of the thyroid gland increases, and in old age - vice versa. In men thyroid more than women. But for the latter, it increases during pregnancy, and six months to a year after birth it returns to its original state.

Ticket number 43.

1. Epithelial dental organ, dental papilla, dental sac.(see first question of ticket No. 36)

Ticket number 44.

Testicle: structure and functions.

Testicle (testis) - paired male gonads, in which male reproductive cells are formed - (spermatozoa) and steroid hormones, mainly testosterone.

Functions: generative (formation of sperm) and endocrine (formation of hormones).

It is covered with a thick connective tissue capsule (tunica albuginea) containing smooth muscle. cells and the giving septum (septum), which divide the organ into 150-250 conical lobules, converging at the tips in the mediastinum of the testicle. Each lobule contains 1-4 convoluted tubules, in which Spermatogenesis.

At the apex of the lobule, the convoluted tubules continue into straight tubules; they are not In spermatogenesis and phenomena. The initial section of the vas deferens. Merging straight tubules open. Into the testicular network in its mediastinum, from where the efferent tubules extend into the epididymis. The space between the convoluted tubules is filled with loose fibrous tissue containing vessels, nerves and interstitial endocrinocytes (Leydig cells), produced by men. floor. hormones - androgens.

Convoluted seminiferous tubules have a complexly organized wall consisting of spermatogenic cells lying in 4-8 layers on the basement membrane and associated with supporting cells. Outside to the basal. membrane - myoid peritubular cells and fibrocytes and elastic. Fibers. During contraction, sperm are propelled into the testicular network.

3. Lymphocytes - cells of the immune system, which are a type of leukocyte of the agranulocyte group, white blood cells. Lymphocytes are the main cells of the immune system, providing humoral immunity (production of antibodies), cellular immunity (contact interaction with victim cells), and also regulate the activity of other types of cells. Normally, in the blood of an adult, lymphocytes account for 20-35% of all white blood cells (see. Leukocyte formula), or in absolute form 1000-3000 cells/µl. At the same time, about 2% of the lymphocytes in the body are in free circulation in the blood, and the remaining 98% are in the tissues.

There are three main types of lymphocytes: T lymphocytes, B lymphocytes and zero lymphocytes (0 cells).

T-lymphocytes are the largest population of lymphocytes; they differentiate in the thymus, enter the blood and lymph and populate T-zones in the peripheral organs of the immune system - lymph nodes, spleen, and follicles of various organs. T-lymphocytes are characterized by the presence of special receptors on the plasmalemma that are capable of specifically recognizing and binding antigens. In the population of T-lymphocytes, several functional groups of cells are distinguished: cytotoxic lymphocytes (TC), or T-killers (Tk), T-helpers (Tx), T-suppressors (Ts). TKs participate in cellular immunity reactions, ensuring the destruction (lysis) of foreign cells and their own altered cells. Receptors allow them to recognize proteins of viruses and tumor cells on their surface.

B lymphocytes are the main cells involved in humoral immunity. In humans, they are formed from red bone marrow HSCs, then enter the blood and further populate the B-zones of peripheral lymphoid organs - the spleen, lymph nodes, and lymphoid follicles of many internal organs. When exposed to an antigen, B lymphocytes in peripheral lymphoid organs are activated, proliferate, and differentiate into plasma cells that actively synthesize antibodies of various classes that enter the blood, lymph, and tissue fluid.

4. The concept and significance of extra-embryonic organs.(see the fourth question of ticket No. 43).

Ticket number 45.

1. Gill apparatus, slits, arches and their derivatives.(see the first question of ticket No. 34).

Gill apparatus - the basis for the formation of the facial part of the head - consists of 5 pairs of gill pouches and gill arches, while the 5th pair of gill pouches and arches in humans is a rudimentary formation. Gill pouches are protrusions of the endoderm of the lateral walls of the cranial portion of the foregut. Toward these protrusions of the endoderm, protrusions of the ectoderm of the cervical region grow, as a result of which gill membranes are formed. Areas of mesenchyme located between adjacent gill pouches grow and form 4 roller-like elevations on the anterior surface of the embryo's neck - gill arches, separated from each other by gill pouches. They grow into the mesenchymal base of each gill arch. blood vessels and nerves. Muscles and cartilaginous bones develop in each arch.

The second largest gill arch is the first, called the mandibular arch. From it the rudiments of the upper and lower jaws, as well as the malleus and incus, are formed. The second gill arch is the hyoid. From it the small horns of the hyoid bone and stapes develop. The third branchial arch is involved in the formation of the hyoid bone (body and large horns) and thyroid cartilage, the fourth, the smallest, is skin fold, covering the lower gill arches and fused with skin neck. Posterior to this fold a fossa is formed - the cervical sinus, communicating with external environment hole, which later becomes overgrown. Sometimes the hole does not close completely and the newborn is left with a congenital neck fistula on the neck, which in some cases reaches the pharynx.

Organs are formed from the gill pouches: from the 1st pair of gill pouches the lamb cavity and the auditory tube are formed; The 2nd pair of gill pouches gives rise to the palatine tonsils; from the 3rd and 4th pairs the rudiments of the parathyroid glands and thymus arise. The rudiments of the tongue and thyroid gland are formed from the anterior sections of the first 3 gill pouches.

2. Digestive canal. Overall plan wall structure.

Alimentary canal - or intestinal canal, the central part of the digestive organs, representing a continuous channel and receiving the ducts of the accessory parts or glands.

The digestive tube in any of its sections consists of an internal mucosa, a submucosa, a muscular layer and an outer membrane, which is represented by either the serosa or the adventitia.

Mucous membrane. Its surface is constantly moistened by mucus secreted by the glands. This membrane consists of three plates: the epithelium, the lamina propria and the lamina muscularis mucosa. Epithelium in the anterior and posterior sections the digestive tube is multi-layered flat, and in the middle section it is single-layered prismatic. The glands are located either endoepithelial (eg, goblet cells in the intestine) or exoepithelial in the lamina propria (esophagus, stomach) and submucosa (esophagus, duodenum) or outside the alimentary canal (liver, pancreas).

lamina propria of the mucous membrane lies under the epithelium, separated from it by the basement membrane and is represented by loose fibrous connective tissue. Here are blood and lymphatic vessels, nerve elements, clusters lymphoid tissue. In some sections (esophagus, stomach) simple glands may be located.

Muscular plate of the mucous membrane located on the border with the submucosa and consists of 1-3 layers formed by smooth muscle cells. In some parts (tongue, gums, except the root of the tongue) there are no smooth muscle cells.

The relief of the mucous membrane throughout the entire digestive canal is heterogeneous. Its surface can be smooth (lips, cheeks), form depressions (dimples in the stomach, crypts in the intestines), folds (in all departments), villi (in the small intestine).

Submucosa. Consists of loose fibrous connective tissue. The presence of the submucosa ensures the mobility of the mucous membrane and the formation of folds. In the submucosa there are plexuses of blood and lymphatic vessels, accumulations of lymphoid tissue and under the mucous nerve plexus. In some sections (esophagus, duodenum) glands are located.

Muscular membrane. It consists of two layers of muscle elements - internal circular and external longitudinal. In the anterior and posterior sections of the digestive canal, the muscle tissue is predominantly striated and, on average, smooth. The muscle layers are separated by connective tissue, which contains blood and lymphatic vessels and the intermuscular nerve plexus. Contractions of the muscle membrane help mix and move food through the digestion process.

Serous membrane. Most of the digestive tube is covered with a serous membrane - the visceral layer of the peritoneum. The peritoneum consists of a connective tissue base in which blood vessels and nerve elements are located, and mesothelium. In some parts (esophagus, part of the rectum) the serous membrane is absent. Here the tube is covered on the outside with an adventitial membrane consisting only of connective tissue.

Ticket number 46.

Structure and functions of the skin.

Function: protective, thermoregulation, participation in water-salt metabolism, synthesis of vitamin D3, excretory, blood deposition, immune and regulatory.

Structure:

Epidermis

The skin itself (dermis) is connected to the underlying tissues by subcutaneous tissue.

Kinds:

Thick skin (palms, soles): has 5 layers (basal, spinous, granular, shiny, horny).

Thin skin: has 4 layers (basal, spinous, granular, horny).

Ticket number 47.

Ticket number 48.

Ticket number 49.

Ticket number 50.

1. Enamel. Microscopic and ultramicroscopic structure and physicochemical properties.(see the first question of ticket No. 50).

Ticket number 51.

Ticket number 52.

Ticket 34.

Gill apparatus, slits, arches and their derivatives.

Gill apparatus - the basis for the formation of the facial part of the head - consists of 5 pairs of gill pouches and gill arches, while the 5th pair of gill pouches and arches in humans is a rudimentary formation. Gill pouches are protrusions of the endoderm of the lateral walls of the cranial portion of the foregut. Toward these protrusions of the endoderm, protrusions of the ectoderm of the cervical region grow, as a result of which gill membranes are formed. Areas of mesenchyme located between adjacent gill pouches grow and form 4 roller-like elevations on the anterior surface of the embryo's neck - gill arches, separated from each other by gill pouches. Blood vessels and nerves grow into the mesenchymal base of each gill arch. Muscles and cartilaginous bones develop in each arch.

Rice. 1. Gill arches and pouches of the embryo at the 5-6th week of development, left view:

1 - ear vesicle (primordium of the membranous labyrinth inner ear); 2 - first gill pouch; 3- first cervical somite (myotome); 4 - kidney of the hand; 5 - third and fourth gill arches; 6 - second gill arch; 7 - cardiac protrusion; 8- mandibular process of the first branchial arch; 9 - olfactory fossa; 10 - nasolacrimal groove; 11 - maxillary process of the first branchial arch; 12 - rudiment of the left eye.

The largest gill arch is the first, called the mandibular arch. From it the rudiments of the upper and lower jaws, as well as the malleus and incus, are formed. The second gill arch is the hyoid. From it the small horns of the hyoid bone and stapes develop. The third branchial arch is involved in the formation of the hyoid bone (body and large horns) and thyroid cartilage, the fourth, smallest, is a skin fold that covers the lower branchial arches and fuses with the skin of the neck. Posterior to this fold, a fossa is formed - the cervical sinus, communicating with the external environment through an opening, which later becomes overgrown. Sometimes the hole does not close completely and the newborn is left with a congenital neck fistula on the neck, which in some cases reaches the pharynx.

The development of the facial skull and brain skull should be considered separately, since they have independent embryonic rudiments, structural features and functions, although topographically they are in close relationships. In the construction of the brain skull, a more ancient formation takes part - the base of the skull, which goes through the cartilaginous stage of development, with which the capsules of the sensory organs and phylogenetically younger bones of the cranial vault and face, ossifying on the basis of membranous connective tissue, are associated. The base and vault of the skull take part in the formation of the bone container for the central nervous system and protect the brain from damage.

Development of the brain part of the skull. The bones of the base of the skull go through three stages of development: membranous, cartilaginous and osseous.

Primary segmentation in the head region of embryos is observed only in the occipital part, where at the level of the hindbrain an accumulation of mesenchyme appears around the notochord (Fig. 69). As the brain grows, the surrounding mesenchyme also develops; its deep layer serves as a derivative of the meninges, and the outer one turns into a membranous skull. The membranous skull in some aquatic animals persists throughout life, but in humans it is found only in the embryonic period and after birth in the form of fontanelles and layers of membranous tissue between the bones. During this period, the developing cerebral hemispheres do not encounter obstacles from the membranous skull.

69. Schematic diagram of precartilaginous accumulations of mesenchyme in a human embryo 9 mm long (according to Bardin).

1 - chord;
2 - occipital complex;
3 - III cervical vertebra;
4 - blade;
5 - hand bones;
6 - palmar plate;
7 - VII rib;
8 - I lumbar vertebra;
9 - pelvis;
10 - leg bones;
11 - sacral vertebrae.

70. Formation of the prechordal and perichordal plates of the developing skull.

1 - prechordal plates (crossbars);
2 - perichordal plates;
3 - chord;
4 - olfactory capsule;
5 - optic fossa;
6 - auditory capsule;
7 - main pharyngeal canal.

At the 7th week of intrauterine development, the transformation of the membranous tissue of the base of the skull into cartilaginous tissue is observed, while the roof and facial part remain membranous. The cartilaginous tissue of the base of the skull is divided into cranial crossbars lying in front of the chord - prechordal and at the edges of the chord - parachordal plates and capsules of the sensory organs (Fig. 70). During this period of development of the skull, blood vessels and nerves grow into its cartilaginous base and take part in the formation of future holes, crevices and canals of the bones of the base of the skull (Fig. 71. A, B). The cranial bars and parachordal plates fuse into a common plate, which has an opening in the place of the future sella turcica, located near the anterior end of the chord. Through this opening pass the cells of the posterior wall of the pharynx, forming the anterior lobe of the pituitary gland. The common cartilaginous plate also fuses with the olfactory, ocular and auditory capsules and with the membranous roof of the skull. The anterior end of the cartilaginous base of the skull is transformed into a vertical plate between the olfactory capsules in the form of the future nasal septum.

Later, at 8-10 weeks of intrauterine development, bone points appear in the cartilaginous base and roof of the membranous skull (see Development of individual bones of the skull).

71. Cartilaginous base of the skull (according to Hertwig).
A - embryo 7 weeks; B - fetus 3 months; 1 - olfactory capsule; 2 - ethmoid bone; 3 - superior orbital fissure; 4 - large wing of the sphenoid bone; 5 - sella turcica; 6 - torn hole; 7 - auditory capsule; 8 - jugular foramen; 9 - internal auditory opening; 10 - foramen magnum.

Development of the facial part of the skull. The development of facial bones must be considered and compared with the development and structure of the bones of aquatic animals. They retain the gill apparatus throughout their lives, and in the human embryo its rudiments exist relatively a short time. In humans and mammals, during the development of the membranous base and cranial vault, seven gill arches are formed. During this period, the facial skull has many similarities with the skull of a shark (Fig. 72).

72. Shark skull (according to E. Gundrich).
1 - brain skull; 2 - opening for the exit of II, III, IV and V pairs of cranial nerves; 3 - palatoquadrate cartilage; 4 - Meckel's cartilage; 5 - infratemporal cartilage; 6 - hyoid cartilage; 7 - the hyoid cartilage itself; I - VII - gill arches.

The differences are that the shark has an open connection between the outer and inner gill pouches. In the human embryo, the gill slits are closed by connective tissue. Subsequently, the gill arches form various organs(table 2).

Table 2. Derivation of gill arches (according to Braus)

Skull formations existing in the embryonic period in aquatic animals	Formations of the skull that exist in adult aquatic animals and in the embryonic period in humans	Derivation of gill arches in humans
I gill arch	Dorsal cartilage Ventral cartilage	Incus (auditory ossicle) Lower jaw Hammer (auditory ossicle)
II gill arch	Sublingual cartilage ( top part) Hyoid cartilage ( Bottom part)	Stapes (auditory ossicle) Styloid process temporal bone, lesser horns of the hyoid bone, stylohyoid ligament
Cavity between I and II gill arches	Bryzgaltse	Tympanic cavity Eustachian tube
III gill arch	Gill arch Unpaired cartilage for connecting the gill arches	Big horns hyoid bone, body of the hyoid bone
IV branchial arch	Gill arch	Thyroid cartilage of the larynx
V branchial arch	» »
VI branchial arch	Gill arches in aquatic animals
VII gill arch	» »	Are being reduced

Thus, only part of the bones of the facial skull (lower jaw, hyoid bone, auditory ossicles) develops from the branchial apparatus.

The process of formation of the facial skull can be traced in the human embryo and lower animal species. Using the example of the development of the skull, one can be convinced that man has gone through a complex path of evolutionary development from an aquatic ancestor to a terrestrial animal. Balfour and Dorn showed that the head represents a transformed anterior end of the body, which, before the development of the central nervous system, had the same structure as the whole body and was segmented. With the formation of the sense organs and the brain at the anterior end of the body and the corresponding transformation of the gill arches into the maxillary and submandibular arches, the vertebral sections of the notochordal part of the head fused with each other and provided the basis for the skull. Consequently, the prechordal and parachordal plates are transformed parts of the axial skeleton.

Gill apparatus and its derivatives. Development of the oral cavity. gill apparatus and its derivatives

Language development

Anatomy

Fish

Embryology

Fish

Amphibians

Reptiles

Birds

Mammals

Homo sapiens

see also

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Literature

An excerpt characterizing the Gill arches