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The pituitary gland has two lobes: anterior pituitary gland (adenohypophysis) and posterior pituitary gland (neurohypophysis).
1
. Anterior pituitary gland. The anterior pituitary gland is divided into three parts: ( a)
anterior adenohypophysis, (b)
intermediate part of adenohypophysis, (in)
tuberal adenohypophysis.
(a) The anterior part of the adenohypophysis is formed by accumulations of epithelial cells, forming branched strands - trabeculae, as well as irregular follicles. Between the clusters of cells are sinusoidal blood capillaries. The thin walls of the sinusoids are formed by loose fibrous connective tissue. Trabeculae and follicles contain glandular cells - endocrinocytes.
There are three types of trabecular endocrinocytes. Endocrinocytes, located on the periphery of cell clusters, contain secretory granules in their cytoplasm, which are easily stained. In this regard, such cells are called chromophilic endocrinocytes. Endocrinocytes, occupying the middle of the cell cluster, have indistinct boundaries, since their cytoplasm is weakly stained. Such cells are called chromophobic endocrinocytes.
Secretory granules of chromophilic endocrinocytes can be stained with either basic or acidic dyes. In accordance with this, chromophilic endocrinocytes are divided into basophilic and acidophilic. Granules of endocrinocytes contain glycoproteins, which are the material for the biosynthesis of hormones. Relatively large basophilic endocrinocytes normally make up ~4 ÷ 10% of the total number of adenocytes. There are two types of basophilic endocrinocytes.
Cells of the first variety are characterized by a round or oval shape and an eccentric position of the nuclei. Their secretory granules have a diameter of ~200 ÷ 300 nm. The number of basophilic endocrinocytes increases with the intensive production of gonadotropic hormones (gonadotropins). For this reason, these cells are called gonadotropocytes, or gonadotropic endocrinocytes. Some of the gonadotropocytes produce follicle-stimulating hormone (follitropy n), and others - luteinizing hormone (lutropin). Follitropin is a means of controlling the formation of germ cells. Lutropin is a stimulant for controlling the formation of the corpus luteum in the ovary, as well as a means for controlling the production of male sex hormone by the interstitial cells of the testis.
Basophilic cells of the second variety differ in irregular shape. Their secretory granules are very small (diameter ~80 ÷ 150 nm) and stain easily with aldehyde fuchsin. These granules contain less glycoproteins than gonadotropocyte granules. Cells of the second type produce thyrotropic hormone - thyrotropin. Thyrotropin is a stimulating means of controlling the functions of follicular endocrinocytes of the thyroid gland. Hence, the cells that secrete thyrotropin are called thyrotropocytes, or thyrotropic endocrinocytes.
Acidophilic endocrinocytes contain large dense protein granules that are easily stained with acidic dyes. These cells are somewhat smaller in size than basophilic endocrinocytes. Their number is ~30 ÷ 35% of all adenocytes of the anterior pituitary gland. They are round or oval in shape. The nuclei of basophilic endocrinocytes are located in the center of the cell. They have a well-developed granular endoplasmic reticulum. Acidophilic endocrinocytes also have two varieties. The first type of acidophilic endocrinocytes - somatotropocytes, or somatotropic endocrinocytes. Some somatotropocytes produce a growth hormone, or growth hormone. Somatotropin is a means of controlling the body's growth. Other growth cells produce lactotropic hormone, or prolactin and therefore they are called accordingly mammotropocytes, or mammotropic endocrinocytes and prolactinocytes, or prolactotropic endocrinocytes. Lactotropic hormone (prolactin) is a means of controlling the biosynthesis of milk in the mammary gland. The intensity of prolactin secretion increases in women in labor after childbirth, during lactation and feeding the newborn. In addition, prolactin prolongs the existence and function of the corpus luteum in the ovary. Secretory granules of somatotropocytes have a spherical shape. Their diameter is ~350 ÷ 400 nm. Mammotropocytes are distinguished by even larger oval or elongated granules (length ~500 ÷ 600 nm, width ~100 ÷ 120 nm).
Chromophilic endocrinocytes include another group of cells located mainly in the central part of the anterior pituitary gland. These cells are called corticotropic endocrinocytes, or corticotropocytes. They work out adrenocorticotropic hormone (ACTH, or corticotropin). Adrenocorticotropic hormone is a stimulating agent for controlling the secretion of hormones by the cells of the zona fasciculata of the adrenal cortex. Corticotropocytes have an irregular shape, lobulated nuclei, and a well-developed endoplasmic reticulum. Their secretory granules have the structure of vesicles containing a dense protein core in their cavity. A clear space remains between the membrane of the bubble and its core.
Chromophobic cells make up ~60% of the total number of adenocytes. The cytoplasm of chromophobic endocrinocytes stains weakly. It does not show secretory granules. Chromophobic cells have different degrees of development and perform different functions. Among them there are cells that have already begun to specialize in basophilic or acidophilic cells, but have not yet had time to accumulate specific secretory granules. Others, chromophobic cells, on the contrary, are quite specialized, but have lost their basophilic or acidophilic secretory granules due to intense or prolonged secretion. A small number of unspecialized chromophobic cells are referred to as reserve cells.
Among chromophobic cells, stellate (follicle-stellate) cells are found. These are small cells with long branched processes, through which they are connected into a wide-loop network. Some of the processes pass between adjacent endocrinocytes and end on the walls of the sinusoidal capillaries. Sometimes stellate cells cluster into small follicles. Glycoprotein secret accumulates in the cavities of these follicles. On the apical surfaces of such stellate cells (from the side of the lumen of the follicle) there are microvilli.
The functions of the adenohypophysis are controlled by peptides and amines secreted by hypothalamic neurons. These neurosecretory cells are located mainly in the medial zone of the hypothalamus, in its arcuate nucleus, in the medial parvocellular part of the paraventricular and periventricular nuclei.
(b) The middle (intermediate) part of the adenohypophysis is a narrow strip of epithelium. Endocrinocytes of the middle part are able to produce a protein or mucous secretion, which, accumulating between neighboring cells, leads to the formation of follicle-like cysts in the middle part of the adenohypophysis. From the back of the adenohypophysis, the epithelium of the middle part is separated by a thin layer of loose connective tissue.
Endocrinocytes of the middle part of the adenohypophysis produce melanocyte-stimulating hormone (melanocytotropin), as well as lipotropin- a hormone that controls lipid metabolism.
(c) The tuberal portion of the adenohypophysis is adjacent to the pituitary stalk and is in contact with the inferior surface of the median hypothalamic eminence. The tuberal part is formed by epithelial strands, consisting of cubic cells with moderately basophilic cytoplasm. Trabeculae extend from the tuberal cords into the anterior part of the adenohypophysis, as well as from the epithelium of the middle part. Basophilic granules are found in some cells of the tuberal cords.
reabsorption in the urinary tubules of the kidney. Oxytocin is a means of controlling uterine muscle contraction. The axons of the neurosecretory cells of the anterior hypothalamus are collected in the hypothalamic-neurohypophyseal bundles, enter the posterior pituitary gland, where they end with large terminals (Herring's bodies, or storage bodies) on the walls of the hemacapillaries.
Percy Theodore Herring (1872-1967), physiologist, physician, UK.
(tuber cinereum, PNA, BNA, JNA)
the department of the hypothalamus, which forms a hollow protrusion of the lower wall of the third ventricle, located in front of the mastoid bodies and connected through a funnel with the pituitary gland; in S. b. are the nuclei of gray matter, which are higher centers vegetative functions (metabolism, thermoregulation).
Watch value Gray Hillock in other dictionaries
Grey- steel
lead
murine
mousey
ashen
smoky
ball
wild
Synonym dictionary
hillock- m. tubercle, tubercle, tubercle will diminish. any sloping elevation, elevation, hump, hill, mound; heap. , on earth, less than a hill: marmot, mole ........
Dahl's Explanatory Dictionary
hillock- mound, m. 1. A small hill. Not a single village around, bald hillocks, and steppe kites sitting on the hillocks. Neverov. 2. Elevation on the water surface. The tornado raised the water in mounds.
Explanatory Dictionary of Ushakov
Grey- about color, an admixture of black, dark to white; shades of gray are different, but there are two main ones: izbur and izinya: izbura gray, brown gray: grey Wolf, gray hare, gray (unpainted) ........
Dahl's Explanatory Dictionary
Grey- gray, gray; grey, grey, grey. 1. Colors that are obtained by mixing black with white. Gray cloth. Gray paper. Grey eyes. Gray clouds. ox. You are gray (to the wolf), and I, buddy, are gray .........
Explanatory Dictionary of Ushakov
Bugor M.- 1. A small hill, a hill. // Any elevation on the surface of smth. 2. Bulge on smth. (usually in humans, animals).
Explanatory Dictionary of Efremova
Light Gray App.— 1. Gray (2*1) with a light shade.
Explanatory Dictionary of Efremova
Dark Gray App.- 1. Gray with a dark tint.
Explanatory Dictionary of Efremova
hillock- -gra; m.
1. A slight elevation, a bulge on the surface of smth. Shore in sand mounds.
2. Trad.-nar. Hill, hill. Behind the hillock is a village. The house is on a hillock.
3. only........
Explanatory Dictionary of Kuznetsov
light gray— oh, oh. Gray (1 digit) with a light tint. Light gray suit. Light gray blouse.
Explanatory Dictionary of Kuznetsov
Grey- -th, -th; ser, -a, -o.
1. Colors of ash, smoke, asphalt, mouse; middle between black and white. S wool. S eyes. S cloud. S building. C-streak of rain. S. cat. S rat.........
Explanatory Dictionary of Kuznetsov
Gray Market- unofficial
quote and
exchange valuable papers according to their expected
exchange rate before the official
release to the stock exchange.
Economic dictionary
Gray Knight— A company-absorber, which, pursuing its own
interests, trying to lower the price
proposals of the "white knight" (white knight), but is for the company -
object
........
Economic dictionary
Gray Knight ("Grey Knight")- An adversary challenger in a battle to take control of another company whose final intentions have not been announced. The initial unwanted challenger is called ........
Economic dictionary
Gray Market ("grey market")— 1. Any market for scarce goods that differs from the "black market" in that it is legal, since the "black market" is usually illegal. 2. Stock market, which ........
Economic dictionary
Greymail ("Grey Blackmail")— See: greenmail (“green blackmail”).
Economic dictionary
Gray Market- (slang) -1) an unofficial market, or a market that is not subject to official control; differs from the black market in that it is legal; characterized by the sale of ........
Law Dictionary
Tubercle of the Maxilla- (tuber maxillae, PNA, BNA, JNA) lower-posterior protrusion of the infratemporal surface of the body of the upper jaw; site of attachment of the oblique head of the lateral pterygoid muscle.
Big Medical Dictionary
Calcaneus- (tuber calcanei, PNA, BNA, JNA; synonym calcaneal tubercle) the back of the calcaneus, ending in the form of a rough protrusion; on the plantar surface bears two processes (medial and lateral).
Big Medical Dictionary
Mound of the Worm- (tuber vermis, PNA, BNA, JNA) a protrusion on the lower surface of the cerebellar vermis.
Big Medical Dictionary
Occipital protuberance External- (protuberantia occipitalis externa) see External occipital protrusion.
Big Medical Dictionary
Visual Hillock- (thalamus, PNA, BNA, JNA) see Thalamus.
Big Medical Dictionary
Brain Infarction Gray- (i. cerebri griseus) see White cerebral infarction.
Big Medical Dictionary
Heart Attack Gray- (i. griseus) see Anemic infarction.
Big Medical Dictionary
Frontal Hillock- (tuber frontale, PNA, BNA, JNA) a paired elevation on the outer surface of the scales of the frontal bone, corresponding to the location of the ossification nuclei.
Big Medical Dictionary
calcaneal tuberosity- (tuber calcanei) see Tuber calcaneus.
Big Medical Dictionary
Omental Hillock- (tuber omentale, PNA, BNA, JNA) 1) a protrusion on the anterior surface of the pancreas near the junction of its body with the head; adjacent to the stuffing bag; 2) elevation on the visceral ........
Big Medical Dictionary
Ischial tuberosity- (tuber ischi adicum, PNA, BNA; tuber ossis ischii, JNA) protruding downward thickening of the ischium at the junction of its body and branches; site of attachment of the sacrotuberous ligament, semitendinosus, ........
Big Medical Dictionary
Gray Hillock- (tuber cinereum, PNA, BNA, JNA) department of the hypothalamus, forming a hollow protrusion of the lower wall of the third ventricle, located in front of the mastoid bodies and connected by ........
Big Medical Dictionary
zygomatic tubercle- (tuber zygomaticum) protruding part of the lateral surface of the zygomatic bone.
Big Medical Dictionary
2. Hypothalamus (hypothalamus) - a relatively small, but extremely important formation of the brain. It contains nuclei containing cells responsible for regulating body temperature, various types of metabolism: water, fat, carbohydrate, etc., the activities of vital body systems (cardiovascular, digestive, vegetative, endocrine), as well as neurosecretory cells that produce many hormones.
Borders of the hypothalamus. In front, the hypothalamus borders on the optic chiasm; the posterior border is the mastoid bodies (corpora mamillaria), laterally it is limited by the visual tracts (trr. optici). The upper limit is the hypothalamic groove (sulcus hypothalamicus), which runs from the interventricular orifice (for. interventriculare) to the entrance to the cerebral aqueduct. The lower border or bottom of the third ventricle (ventriculus tertius) is represented by a gray tubercle (tuber cinereum) lying in front of the mastoid bodies. The gray tubercle extends into a funnel (infundibulum), on which the pituitary gland (hypophysis) hangs (Fig. 467).
470. Scheme of the main nuclei of the hypothalamus.
1 - chiasma opticum; 2 - nucl. supraopticus; 3 - nucl. suprachiasmaticus; 4 - nucl. preopticus; 5 - commissura cerebri anterior; 6 - nucl. paraventricularis; 7 - nucl. superomedialis; 8 - nucl. inferomedialis; 9 - nucl. corporis mamillaris; 10 - nucl. premamillaris; 11 - nucl. periventricularis; 12 - nucl. tuberis: 13 - nucl. posterior.
The mastoid bodies are paired elevations located in front of the posterior perforated substance. In the nuclei of these bodies, olfactory fibers switch, heading to the nuclei of the anterior zone of the visual tubercle, the suprathalamic region and the tegmentum of the midbrain.
The gray tubercle is a thin-walled part of the bottom of the third ventricle, located between the mastoid bodies and the optic chiasm. Anteriorly, the gray tubercle passes into a thinned end plate (lamina terminalis). It is stretched between the optic chiasm and the anterior cerebral commissure. In the nuclei of the gray hillock there are higher mechanisms of regulation of the autonomic part of the nervous system.
The visual part (pars optica) of the hypothalamus includes the optic chiasm (chiasma opticum), the right and left visual tracts (trr. optici).
The subthalamic body (corpus subthalamicum) has an oval shape, is located under the lateral zone of the visual mound medial to the lenticular body. It is especially well seen on the frontal cuts of the brain.
The gray matter of the hypothalamus is located around the cavity of the third ventricle of the brain at different depths from its wall and includes more than 32 nuclei. The largest nuclei (Fig. 470) are:
a) the supervising nucleus (nucl. supraopticus), paired, is located lateral to the medial plane above the optic tract from the beginning of the optic tract decussation and extends to the middle of the gray tubercle; the cells of this nucleus produce antidiuretic hormones;
b) the paraventricular nucleus (nucl. paraventricularis), paired, in the form of a plate, is located slightly above the third ventricle. Its lower part begins at the level of the optic chiasm, then goes up and back. The processes of the neurosecretory cells of the oversight and paraventricular nuclei form the hypothalamic-pituitary bundle, which descends along the pituitary stalk to the posterior lobe of the pituitary gland. Receptors of neurosecretory cells are in contact with the blood vessels of the pituitary gland. Neuroserets, penetrating into the blood, excite the cells of its anterior lobe through the portal system of the pituitary gland.
c) the superomedial nucleus (nucl. superomedialis), paired, is located directly behind the paraventricular nucleus, but somewhat deeper;
d) the lower medial nucleus (nucl. inferomedialis), paired, is located somewhat posteriorly and lower than the upper medial. The cells of the superomedial and inferomedial nuclei have adhesive neurons that are in contact with neurons on the opposite side. The functional significance of these two nuclei lies not only in the formation of neurosecrets that affect the adrenal glands. They are intercalary neurons that transmit impulses to the hypothalamus and neurosecretory cells, that is, they transmit impulses to effector neurons that go to the nuclei of the brain stem and spinal cord as part of the medial and posterior longitudinal bundles (fasculi longitudinales medialis et lateralis);
e) the lateral periventricular nucleus (nucl. periventricularis) is located in the wall of the third ventricle at the level and slightly above the infundibulum of the pituitary stalk, behind the lower medial nucleus;
e) the core of the tubercle (nucl. tuberis) is located in front of the base of the funnel. The neurons of the nucleus are sent to the median eminence (eminentia medialis), which is localized in the anterior wall of the pituitary funnel on the border with the gray tubercle. The median eminence is formed by neuroglia, which contains numerous fibers of the infundibulum nucleus, which form axon-vascular contacts in the primary plexus of the pituitary system;
g) the posterior nucleus (nucl. posterior) is large, paired, lies behind the superomedial nucleus, extends to the beginning of the cerebral aqueduct. In this nucleus, as well as in the epithelium and paraventricular nuclei, the body's water-salt metabolism is regulated;
h) the nuclei of the mastoid body (nucl. corporis mammillaris) are located in the mastoid bodies. There are several more small nuclei located in front of and above the medial mastoid nucleus. The nuclei switch impulses from the olfactory analyzer to the nuclei of the thalamus.
Age features of the diencephalon. In newborns, the thalamus is well developed. Its fibers are completely covered with myelin by the 6th month of life. By the time of birth, the nuclei of the hypothalamus are differentiated, the pituitary gland and the pineal gland are well developed.
GRAY BUCK
(tuber cinereum, pna, bna, jna) department of the hypothalamus, forming a hollow protrusion of the lower wall of the third ventricle, located in front of the mastoid bodies and connected through a funnel to the pituitary gland; in S. o. there are nuclei of gray matter, which are the highest centers of vegetative functions (metabolism, thermoregulation).
Medical terms. 2012
See also interpretations, synonyms, meanings of the word and what is GRAY BUGOR in Russian in dictionaries, encyclopedias and reference books:
- GREY in the Dictionary of Russian Railway Slang:
auxiliary ... - GREY
- a person who committed for the first time ... - BUGOR in the Dictionary of thieves' jargon:
- 1) foreman in ITU, 2) authority in a criminal environment, 3) senior in ... - GREY in the Dictionary of Economic Terms:
MARKET (slang) - 1) an unofficial market, or a market that is not subject to official control; differs from the black market in that it is... - GREY in encyclopedic dictionary:
, -th, -th; grey, grey, grey. 1. Colors of ash, smoke. Gray clouds. Gray overcoat. S. wolf. Grey eyes. C. bread ... - BUGOR in the Encyclopedic Dictionary:
, -gra, m. 1. A slight elevation, a hill. 2. Slight bulge, roundness. Bumps on the skin. * Over the hillock, over the hillock, because of ... - GREY
GRAY CAST IRON, see Cast iron ... - GREY in the Big Russian Encyclopedic Dictionary:
GRAY SEAL, the same as tevyak ... - GREY in the Big Russian Encyclopedic Dictionary:
GRAY PARROT, the same as Zhako ... - GREY in the Big Russian Encyclopedic Dictionary:
GRAY WHALE (California whale), sea. mammal podtr. toothless whales. Length up to 15 m. Lives in coastal waters sowing parts of the Pacific... - GREY in the Big Russian Encyclopedic Dictionary:
GRAY WOLF, the same as a wolf ... - GREY
se"ry, se"paradise, se"swarm, se"rye, se"horn, se"swarm, se"horn, se"ryh, se"rum, se"swarm, se"rum, se"rym, se" ry, se"ruyu, se"swarm, se"rye, se"horn, se"ruyu, se"swarm, se"ryh, ... - BUGOR in the Full accentuated paradigm according to Zaliznyak:
bugo "r, hillocks", hillock", hillock "in, hillock", hillock "m, bugo" r, hillocks ", hillock" m, hillock "mi, hillock", ... - GREY in the Thesaurus of Russian business vocabulary:
- GREY in the Russian Thesaurus:
Syn: poorly educated, unenlightened Ant: … - GREY
cm. … - BUGOR in the Dictionary of synonyms of Abramov:
see hill, ... - GREY
Syn: poorly educated, unenlightened Ant: … - BUGOR in the dictionary of Synonyms of the Russian language:
boss, tubercle, tubercle, eminence, elevation, bulge, hydrolaccolith, director, inion, kuchugur, head, cartridge, hillock, head, tepe, hill, mound, ... - GREY
1. m. Ash-colored animal. 2. adj. 1) a) Having a color obtained by mixing black with white. b) ... - BUGOR in the New explanatory and derivational dictionary of the Russian language Efremova:
m. 1) a) A small hill, a hill. b) Any elevation on the surface of smth. 2) Bulge on smth. (usually a person... - GREY
s`ery 2, th (oh ... - BUGOR in the Dictionary of the Russian Language Lopatin:
bug'or, ... - BUGOR in the Complete Spelling Dictionary of the Russian Language:
hillock, ... - GREY in the Spelling Dictionary:
s`ery 2, th (oh ... - GREY in the Spelling Dictionary:
s`ery 1; cr. f. ser, ser, ... - BUGOR in the Spelling Dictionary:
bug'or, ... - GREY
mediocre, unremarkable Gray existence. Gray story. gray About the weather: overcast Gray weather. C. day. positive; unfold joke). grey … - BUGOR in the Dictionary of the Russian Language Ozhegov:
slight elevation, hillock hillock slight bulge, roundness Hillocks on … - GRAY in Dahl's Dictionary.
- BUGOR in Dahl's Dictionary:
husband. tubercle, tubercle, tubercle will diminish. , hillock, hillock led away. any sloping elevation, elevation, hump, hill, mound; heap. Hillock, on the ground, ... - GREY
gray, gray; grey, grey, grey. 1. Colors that are obtained by mixing black with white. Gray cloth. Gray paper. Grey eyes. … - BUGOR in the Explanatory Dictionary of the Russian Language Ushakov:
hillock, m. 1. A small hill. Not a single village around, bald hillocks, and steppe kites sitting on the hillocks. Neverov. 2. Elevation... - GREY
gray 1. m. Ash-colored animal. 2. adj. 1) a) Having a color obtained by mixing black with white. … - BUGOR in the Explanatory Dictionary of Efremova:
hillock m. 1) a) A small hill, a hill. b) Any elevation on the surface of smth. 2) Bulge on smth. (usually a person... - GREY
- BUGOR in the New Dictionary of the Russian Language Efremova:
m. 1. A small hill, a hill. ott. Any elevation on the surface of something. 2. A bulge on something (usually in a person, ... - GREY
I m. Ash-colored animal. II adj. 1. Having a color obtained by mixing black with white. ott. trans. … - BUGOR in the Big Modern explanatory dictionary Russian language:
I m. 1. A small hill; slide. 2. Any elevation on the surface of something. II m. Foreign countries, foreign countries; … - BUGOR VASILY in the Brief Biographical Encyclopedia:
Bugor (Vasily) - Cossack, walked along Northeast Siberia(about half of the 17th century) to collect yasak. A petition to the sovereign has been preserved from him, ... - calcaneal tuberosity in Medical terms:
(tuber calcanei) see Calcaneal tuberosity ... - BUCK OF THE CANEAL BONE in Medical terms:
(tuber calcanei, pna, bna, jna; synonym for calcaneal tubercle) the back of the calcaneus, ending in the form of a rough protrusion; on the sole surface... - BORAT SAGDIEV in Wiki Quote.
- CAST IRON
(Turk.), an alloy of iron with carbon (usually more than 2%) containing also permanent impurities (Si, Mn, P and S), and sometimes ... - AGREEMENT (GRAMMATIC) in big Soviet encyclopedia, TSB:
1) the presence of a certain correspondence between the grammatical form of a noun (or its belonging to a certain syntactic class) and the grammatical form associated with ... - BODY COLOR in the Encyclopedic Dictionary of Brockhaus and Euphron.
- PALMISTRY
Palmistry is the art of determining the character of a person and predicting his fate from the lines, wrinkles, folds and bumps that cover the palm of your hand. Coming from a deep... - SHRINKAGE OF METALS in the Encyclopedic Dictionary of Brockhaus and Euphron:
The volume of hard metal at ordinary. pace. always less than its volume in the molten state. This is the property of molten metals to reduce their volume ... - pelvis, in anatomy in the Encyclopedic Dictionary of Brockhaus and Euphron:
(pelvis) - a set of bones, or cartilage, or, finally, one cartilage (pelvic cartilage), which serve to attach the posterior pair of vertebrate limbs and ...
The hypothalamus is the ventral part of the diencephalon. It consists of a complex of formations located under the third ventricle. The hypothalamus is bounded anteriorly by the optic chiasm (chiasm), laterally by the anterior part of the subthalamus, the internal capsule, and the optic tracts extending from the chiasm. Posteriorly, the hypothalamus continues into the midbrain tegmentum.
In the hypothalamus, a larger anterolateral part and a smaller posterior part are distinguished. The anterolateral part forms the floor of the third ventricle of the brain and includes a gray tubercle, funnel with pituitary gland, optic tracts, optic chiasm, and borderline brain plate. This also includes the actual hypothalamic region - the accumulation of nuclei of the gray matter of the hypothalamus.
The gray tubercle is a thin, convex from below part of the lower wall of the third ventricle, located between the optic chiasm in front and the mastoid bodies behind. Vegetative nuclei are located in the wall of the gray tubercle, which are classified as emotional zones of the brain. The thinned continuation of the anterior wall of the gray tubercle upwards and backwards is a border plate that forms the anterior wall of the third ventricle. Ventral and slightly anteriorly, a gray tubercle forms a funnel, which serves as an attachment point for the pituitary gland.
The hypothalamic region is located under the thalamus just above the gray tubercle and partly inside between its walls. From above, it is separated from the thalamus by the hypothalamic groove. The hypotuberous region contains up to 40 nuclei, the functional role of which is very important.
In the anterior-lateral part of the hypothalamus, the anterior and middle groups of the hypothalamic nuclei are distinguished. The anterior group includes the paraventricular nucleus, the preoptic nucleus, the supraoptic and suprachiasmatic nuclei.
The middle group of nuclei includes the dorsomedial and ventromedial nuclei, the nucleus of the gray tubercle and the nucleus of the funnel. The middle group of nuclei controls water, fat and carbohydrate metabolism, affects blood sugar levels, the ionic balance of the body, the permeability of blood vessels and cell membranes.
The posterior part of the hypothalamus is located between the gray tubercle and the posterior perforated substance and consists of the right and left mastoid bodies. Inside each of them, under a thin layer of white matter, there are two gray nuclei belonging to the subcortical olfactory centers.
The hypothalamus has a wide system of connections with many brain formations, which explains its participation in many behavioral reactions. The system of afferent and efferent fibers of the fornix connects the anterior hypothalamus and mammillary bodies with the hippocampus of the cerebral hemispheres, and the mastoid-thalamic (Vic d'Azira bundle) and mastoid-tubular pathways connect the mastoid bodies with the thalamus and the tegmentum of the midbrain.
The optic chiasm of the hypothalamus is formed when half of the fibers of the optic nerve (II pair of cranial nerves) pass to the opposite side. The optic chiasm on each side continues laterally and posteriorly into the optic tract, which is also a structure of the hypothalamus.
The intersection of the visual tracts is X-shaped, in the chiasm in primates there is a partial decussation of the fibers. Fibers from the nasal half of the retina, including the nasal half of the fovea, cross the midline and travel to the contralateral lateral geniculate body (NKT). Fibers from the temporal half of the retina, including the lateral fovea, remain on their side and are directed to the ipsilateral lateral geniculate body.
The mastoid body is a paired rounded elevation on the basis of the brain (in the hypothalamus region), in which nuclei belonging to the subcortical olfactory centers are contained under the surface layer of white matter.
46.The pituitary gland, its structure and functions. Hypothalamo-pituitary neurosecretory system.Pituitary- a brain appendage in the form of a rounded formation, located on the lower surface of the brain in a bone pocket called the Turkish saddle, produces hormones that affect growth, metabolism and reproductive function. It is the central organoendocrine system; interacts closely with the hypothalamus. The pituitary gland is located at the base of the brain (lower surface) in the pituitary fossa of the Turkish saddle-sphenoid bone-skull. The Turkish saddle is covered by a process of the hard shell of the brain - the diaphragm of the saddle, with a hole in the center through which the pituitary gland is connected to the funnel of the hypothalamus of the diencephalon; through its pituitary gland is connected with a gray tubercle located on the lower wall of the third ventricle. On the sides of the pituitary gland is surrounded by cavernous sinuses. The dimensions of the pituitary gland are quite individual: the anteroposterior / sagittal size ranges from 5 to 13 mm, the upper-lower / coronal - from 6 to 8 mm, the transverse / axial / transversal - from 3 to 5 mm. The pituitary gland consists of two large lobes of different origin and structure: the anterior - adenohypophysis (makes up 70-80% of the mass of the organ) and the posterior - neurohypophysis. Together with the neurosecretory nuclei of the hypothalamus, the pituitary gland forms the hypothalamic-pituitary system that controls the activity of the peripheral endocrine glands. Neurohypophysis (posterior pituitary gland))Neurohypophysis, neurohypophysis, comprises nerve lobe and funnels, fundibulum connecting the nerve lobe with the median eminence. The nerve lobe is formed by ependymal cells (pituicytes) and axon endings of neurosecretory cells paraventricular and supraoptic nuclei of the hypothalamus of the diencephalon, in which vasopressin (antidiuretic hormone) and oxytocin are synthesized, transported along the nerve fibers that make up the hypothalamic-pituitary tract to the neurohypophysis. In the posterior lobe of the pituitary gland, these hormones are deposited and from there they enter the bloodstream. The pituitary infundibulum joins with the hypothalamic infundibulum to form pituitary stalk. Vasopressin performs two functions in the body: 1) Increased water reabsorption in the collecting ducts of the kidneys (this is the antidiuretic function of vasopressin); 2) the effect on the smooth muscles of arterioles, however, the name "vasopressin" does not quite correspond to the property of this hormone to constrict blood vessels. The fact is that in normal physiological concentrations it does not have a vasoconstrictive effect. Vasoconstriction can occur with the exogenous introduction of the hormone in large quantities or with blood loss, when the pituitary gland intensively secretes this hormone. With insufficiency of the neurohypophysis, a syndrome of diabetes insipidus develops, in which a significant amount of water (15 l / day) can be lost in the urine per day, as its reabsorption in the collecting ducts decreases. Oxytocin during pregnancy does not affect the uterus, because under the influence of progesterone secreted by the corpus luteum, it becomes insensitive to this hormone. Oxytocin promotes the contraction of myoepithelial cells that promote the release of milk from the mammary glands. Adenohypophysis (anterior pituitary gland) Adenohypophysis, consists of glandular endocrine cells various types, each of which, as a rule, secretes one of the hormones. Anatomically, pars distalis (most of the adenohypophysis), pars tuberalis (a leaf-like outgrowth surrounding the pituitary stalk, the functions of which are not clear) and pars intermedia, which is more correctly referred to as an intermediate lobe of the pituitary gland, are distinguished in it. The anterior pituitary gland produces six hormones. The target organs of the four anterior pituitary hormones are the endocrine glands, so they are called tropic hormones. Pituitary hormones stimulate a certain gland, and an increase in the level of hormones secreted by it in the blood suppresses the secretion of the pituitary hormone. Thyroid-stimulating hormone - the main regulator of biosynthesis and secretion of hormones thyroid gland. The adrenal cortex is stimulated by adrenocorticotropic hormone. The other two hormones are called gonadotropic hormones: follicle-stimulating hormone promotes the maturation of follicles in the ovaries, and luteinizing hormone causes ovulation and the formation of a corpus luteum. In addition, the anterior pituitary gland produces two more hormones that act on organ systems and the entire body as a whole. Growth hormone is the most important stimulator of protein synthesis in cells, the formation of glucose and the breakdown of fats, as well as the growth of the body. Luteotropic hormone (prolactin) regulates lactation, differentiation of various tissues, growth and metabolic processes, the instincts of caring for offspring. Intermediate (middle) lobe of the pituitary gland. At many animals have a well-developed intermediate lobe of the pituitary gland, located between the anterior and posterior lobes. It originates from the adenohypophysis. In humans, it is a thin layer of cells between the anterior and posterior lobes, which extends rather deeply into the pituitary stalk. These cells synthesize their own specific hormones. - melanocyte-stimulating and a number of others . Posterior lobe (neurohypophysis). Posterior lobe of the pituitary gland (lat. pars posterior) - endocrine organ, accumulating and secreting hormones that are synthesized in the large cell nuclei of the anterior hypothalamus and pass along the axons to the posterior pituitary gland. The neurohypophyseal hormones in mammals include: vasopressin (or antidiuretic hormone, ADH), which regulates water metabolism and arteriole tone, and also performs a mediator function in some synapses of hypothalamic neurons; oxytocin (or cytocin), which regulates the birth act and the secretion of milk by the mammary glands. In representatives of other classes of vertebrates, the posterior pituitary gland secretes other hormones that differ slightly in chemical structure and biological properties from vasopressin and oxytocin: vasotocin, mesotocin, glumitocin, isotocin, valitocin, asparotocin. The functioning of all parts of the pituitary gland is closely related to the hypothalamus. This provision applies not only to the posterior lobe - the "receiver" and depot of hypothalamic hormones, but also to the anterior and middle sections of the pituitary gland, whose work is controlled by hypothalamic pituitary hormones - releasing hormones. Hypothalamic-pituitary system- the union of the structures of the pituitary and hypothalamus, which performs the functions of both the nervous system and the endocrine system. This neuroendocrine complex is an example of how closely interconnected the nervous and humoral modes of regulation are in mammals. The hypothalamic-pituitary system consists of the pituitary stalk, which begins in the ventromedial region of the hypothalamus, and three lobes of the pituitary gland: the adenohypophysis (anterior lobe), the neurohypophysis (posterior lobe), and the intercalary lobe of the pituitary gland. The work of all three lobes is controlled by the hypothalamus with the help of special neurosecretory cells. These cells secrete special hormones called releasing hormones. The releasing factors enter the pituitary gland, more specifically the adenohypophysis, through the portal vein of the pituitary gland.
