Chromaffin cells. Meaning of medulla

Above the upper pole of the kidneys are small glands known medically as the adrenal glands. Despite the obvious connection with the urinary organs, the functions of the adrenal glands significantly exceed the influence on the functioning of the kidneys.

They are part of numerous endocrine glands, which, along with the nervous and immune systems, control the mechanisms of adaptation to external and environmental conditions in the human body. internal environment, form a reaction to any pathogen (stress).

The work of the adrenal glands is associated with the production and supply of hormones to the blood that are responsible for protecting internal organs by creating an inflammatory reaction, isolating the damaged organ through vasoconstriction, ensuring readiness for physical and nervous stress.

The question of what the functions of the adrenal glands are has been studied in animal experiments. Modern knowledge make it possible to identify individual types of hormones, determine their biological composition and structure, and trace their role in physiological and pathological processes. Moreover, scientists have achieved the synthesis of analogues of adrenal hormones and widely use them in the treatment of serious diseases.

Some historical information

Medical historians disagree about the first descriptions of the adrenal glands in human body. Some believe that the mention of “fat above the kidneys” is in the Bible, others attribute primacy to Claudius Galen. But this scientist only discovered left gland in mammals.

The most eminent doctors occupying high positions in the courts of European states, the Pope, Queen Maria Theresa of Austria, and the French monarch Henry IV did not understand the function of the adrenal glands, generally denied any role for such formations, and even classified them as developmental anomalies.

Only 3 centuries later, a rapid study of the glands began, it was discovered how the adrenal glands are structured, the functions are related to endocrine system. Scottish doctor Thomas Addison managed to prove that the cause of the “bronze” disease, leading to fatal outcome, is their insufficiency. He was the first to identify cancer metastasis to the adrenal glands.

To this day, the names of the two layers that make up the adrenal cortex and the medulla have been preserved. The use of microscopes with improved resolution made it possible in the 19th century to separate the structure and functions of the endocrine glands and establish their connection with the nervous system.

Experimental physiologists studied the functions of the adrenal glands by introducing extracts into experimental animals and removing them.

Modern histological methods have made it possible to isolate special cells of the adrenal cortex. After introduction to medical practice Adrenaline has been around for over 100 years, but research continues. The therapeutic effect of hormones allows us to save the lives of millions of people suffering from diseases and shock conditions.

External structure and appearance of the adrenal gland

The adrenal glands are located inside the fatty tissue at the apex of the kidneys on both sides. There are differences in shape: on the right the iron resembles a triangular pyramid, on the left it resembles a rounded crescent.

When describing it, it is customary to divide it into the outer surface, back, renal.

Left and right gland located asymmetrically with respect to midline body:

on the left - the renal surface is closer to the median edge of the kidney and the formation called the “gate”;
on the right - clearly lies above the upper pole.

The average size of the glands in an adult is 5 cm in length, up to four cm in width, and 1 cm in thickness. The outer layer is a thick, tuberous capsule yellow color. It is attached to the kidney by many dense fibrous strands. In addition, the renal fat capsule and fascia tightly surround the glands.

In the section you can see the division inner fabric(parenchyma) to:

outer cortex- accounts for up to 90% of the entire gland by weight;
internal - medulla.

Dense septa (trabeculae) penetrate deep into the parenchyma through the adrenal cortex.

Anatomical relationships with neighboring organs

The localization of the adrenal glands allows them not only through the blood, but also by contact to come into contact with the most important internal organs. The level is usually determined in relation to the ribs and vertebrae: usually these are the XI and XII vertebrae of the thoracic region, with the right adrenal gland lying slightly lower than the left.

The posterior surfaces of the gland are adjacent to the diaphragm in its lumbar region. The anterior part of the left adrenal gland is in contact with the tail of the pancreas, the cardiac part of the stomach, and closer to the center - with the aorta.

Right - borders the liver in front and duodenum, in the middle - with the inferior vena cava.

Internal organization

The adrenal cortex and medulla are independent glands internal secretion. They are structurally united into one organ, but have different origins and functional purpose. Even development at the embryonic stage occurs independently of each other.

In the eighth week of pregnancy, the future cortex is formed. And in the period from 12 to 16 weeks, sympathochromaffin cells separate from the primary sympathetic nerve trunk and grow into the rudiment of the cortex. The brain matter is formed from them. Chromaffin cells are called so because of their affinity for a certain dye (potassium dichromate).

The cortex can form “accessory” glands in the form of small bodies in utero. They are located in the uterus, ovaries in women, in the epididymis in men, on the inferior vena cava, ureters, nerve fibers solar plexus or on the surface of the adrenal glands in the form of nodules. Not considered true because they do not contain medulla.

Chromaffin cells, united in nodes (paraganglia), in addition to the adrenal medulla, are present in the area of the aortic bifurcation (above and below the division), in the nodes of the sympathetic ganglia, in the bifurcation zone of the common trunk carotid artery.

The cortex is divided into three zones, each of which synthesizes individual species hormones:

closer to the surface there is a thin glomerular layer;
in the middle lies the fascicular zone;
from the inside, the reticular zone is in contact with the medulla.

The medulla receives direct instructions from nervous system. The work of the adrenal cortex is controlled by the pituitary gland through its neuroendocrine hormones, controlled by the hypothalamus. medulla oblongata and the renin-angiotensin system.

Features of blood supply

The kidneys and adrenal glands share a common blood supply. They receive blood through three arteries:

a branch from the inferior phrenic artery - the main adrenal artery;
extending from the abdominal aorta - middle adrenal;
parts renal artery- inferior adrenal gland.

Venous blood flows into the right adrenal vein, which flows into the inferior vena cava, and from the left gland through the left adrenal, renal into the inferior phrenic vein. In surgery abdominal cavity the risk of injury to the right is taken into account renal vein(short) during surgery to remove the adrenal gland.

Age characteristics

Studies have shown the structural features of the adrenal glands in different age periods person. At birth, there are only 2 zones in the cortex:

germinal cortex;
very thin true bark.

Then the entire gland begins to shrink due to the disappearance of the germinal layer. IN adolescence when it goes puberty, the adrenal glands grow in size, their weight reaches 10 g.

IN old age atrophy of the parenchyma of both layers occurs, the glands shrink again.

Functional purpose of the adrenal glands

The functions of the adrenal glands are determined by the synthesis of certain hormones that are active biological substances, influencing all aspects of metabolism, development, growth, synchronizing the activity of human internal organs.

What is the cortex responsible for?

The cortex produces different hormones, depending on the specific site of synthesis, it is ensured by the presence of specific enzymes:

in the glomerular layer - mineralcorticoids (aldosterone);
in the fasciculata - glucocorticoids (11-deoxycorticosterone, cortisol, corticosterone);
in the reticular (reticular) - sex hormones androgens and estrogens.

Mineralcorticoids regulate blood pressure in the body through the tubules renal tissue, sodium retention, increased excretion of potassium and hydrogen ions. In cases of fluid loss due to increased sweating or diarrhea, aldosterone retains sodium by regulating reabsorption in the colon and sweat glands.

In addition, the activating effect of aldosterone on angiotensin II is known. It comes into effect when blood pressure drops below 90 mm Hg. Art.

Glucocorticoids regulate all types of metabolism in the body. The main representative - cortisol - is able to enhance the production of catecholamines in the medulla, glucagon. In response to an increased release of adrenocorticotropic hormone into the blood of the anterior pituitary gland, a sharp stimulation of cortisol synthesis is possible.

The protective effect is manifested in maintaining minimal blood sugar levels during fasting.

Meaning of medulla

The adrenal medulla produces 80% of the body's total adrenaline and 20% norepinephrine. They are synthesized in chromaffin cells. Tyrosine (one of the amino acids) enters the production process. It produces deoxyphenylalanine. Then comes the decarboxylation reaction with the formation of dopamine. From it, under the influence of enzymes, norepinephrine is produced, then adrenaline.

These hormones provide protective mobilization of all systems and organs in case of threat. Activation begins after receiving an “order” from the sympathetic nervous system along the fibers of the thoracic region spinal cord. The cortical hormone cortisol is also involved.

The chain reaction can be represented by the following diagram: an irritant agent regarded by the brain as dangerous → transfer of excitation to the nuclei of the hypothalamus → transfer of the impulse to the spinal sympathetic centers in thoracic region→ spread to nerve fibers→ enters the adrenal medulla and produces adrenaline, norepinephrine (release from granules).

You can learn more about the role of the adrenal glands in humans in this article.

The influence of the adrenal glands on sexual characteristics, the course of pregnancy

Changes in the functioning of the adrenal glands in women concern the reticular zone and the disturbed relationship between the production of estrogens and androgens. For men, androgens determine the development of male sexual characteristics during puberty. Women must have a certain level of testosterone, and men - estrogen. Both types of sex hormones are important in the ability to have offspring and carry a pregnancy to term.

Estrogens are called protectors of the female body. They are produced in the ovaries, and with age-related atrophy - only by the adrenal glands. They allow you to maintain cholesterol metabolism at the required level, preventing the deposition of atherosclerotic plaques in the vessels. During menopause, the adrenal glands are responsible for maintaining estrogen levels without the ovaries.

During pregnancy, the anterior lobe of the pituitary gland doubles in size. It stimulates the activity of the adrenal glands. Regulation is necessary for the fetus water-salt metabolism, which means more mineralcorticoids are required. Maternal physiology is related to the reaction to the fetus, therefore increased synthesis glucocorticoids provide the necessary reduction in immunity to block possible rejection.

A negative effect is observed in the form of increased pigmentation, increased hair growth on the body of the expectant mother, and the formation of striae on the skin.

Physiology of stress and adrenal function

The stress reaction initially has a protective nature and ensures the preparation of all systems and organs to work in extreme conditions for them. But with frequent repetition of “anxiety attacks”, the retinal zone of the cortex is depleted. Adrenal weakness or insufficiency develops.

The body's ability to respond to irritant falls. You should pay attention to such stressful effects as fasting and exhausting physical training.

When fasting, the body protects itself by using the ability to produce glucocorticoids to maintain glucose levels. The biochemical process of glucogenesis occurs with the breakdown of carbohydrates and proteins. The load on the adrenal glands increases significantly. This can only increase the effect of stress and lead to chronic failure, losses vital energy for survival.

It’s not for nothing that professional athletes are monitored by doctors. There are enough cases of the appearance of male sexual characteristics in women with extreme muscle development.

After leaving professional sports Obstetricians and gynecologists receive physically exhausted expectant mothers who require increased attention to be able to give birth to a healthy child.

We should not forget that loss of libido in young people is also an early symptom of adrenal overload.

What indicators are used to evaluate the functioning of the adrenal glands?

When symptoms of adrenal insufficiency or hyperfunction appear, laboratory tests are performed:

Saliva is analyzed four times during the day in separate tubes. It allows you to determine the level of hormone fluctuations.
In the same way, blood serum is examined for cortisol and other hormones.
Adrenaline and cortisol are determined in urine collected per day.
If the level is insufficient, a test with adrenocorticotropic hormone stimulation is performed. It allows you to judge the response of the adrenal glands. An initial blood test is taken, then Corticotropin is administered intramuscularly. After half an hour or an hour, the hormones are re-examined.
At high content carry out a test with Dexamethasone. It is given orally, control tests are carried out after a day or two days.

Adrenal insufficiency problems often occur in patients with long-term illnesses. Therefore, the use of their analogues in treatment is indicated. You cannot put additional stress on your body. The further reaction is unpredictable even for very seasoned people.

Lipoma in the kidney

Kidney lipoma - rare fat formation within the kidney or surrounding tissues. This disease is more often detected in women after 35 years of age and grows to large sizes, causing pain and hematuria. Benign formations have a risk of degenerating into cancerous forms, and treatment involves a complete nephrectomy.

Lipoma is a benign formation of adipocytes in various tissues of the body. The kidneys are a rare location.

The excretory organ consists of two zones:

cortex, or peripheral part;
medulla or medulla oblongata of the inner part.

Tumors are found anywhere, but more often in the cortex, by chance during studies for other reasons.

Manifestations of a wen, depending on the size, can be as follows:

hematuria or blood in the urine;
stomach ache;
frequent infections urinary tract;
vein compression spermatic cord in men;
nagging pain in the lumbar region.

Lipoma on the kidney appears more often in women and is treated surgically. There are no factors that determine predisposition to this pathology.

The reasons for the appearance of single lipomas have not been established by medical science. Such damage is caused by alcohol consumption, smoking, unfavorable environmental conditions, and radiation, including therapeutic radiation. Lipomatosis, or a large number of Lipoma is a genetically determined condition with an autosomal dominant mode of inheritance.

The mechanism of formation of the wen has not been revealed, and the manifestations depend on the size and location. A small kidney lipoma is asymptomatic, but a large one provokes symptoms of urinary tract infections and nephropathy.

Lipomas are most often located in the peripheral part of the kidneys, sometimes extending beyond the organ into the abdominal cavity. The formation has clear boundaries and is separated from other tissues. It is accompanied, in addition to signs of kidney disease, by high blood pressure. Large lesions can seriously impair kidney function and put pressure on neighboring organs and structures, and sometimes penetrate them.

Kidney lipoma is diagnosed accidentally during an X-ray, magnetic resonance imaging (MRI), ultrasound examination (US) for other reasons. Imaging of the tumor requires a complete physical examination, history, ultrasound, and x-rays.

A urine test confirms the presence of blood cells and evaluates kidney function. With the help of a dye injected into the vessels, you can see a clear picture of the organ. Angiographic studies of neoplasm vessels are required.

IN in some cases Invasive diagnostic procedures are used:

Laparoscopic examination involves inserting a device with a camera through a small incision into the abdominal cavity. When tumors are detected, the surgeon immediately performs surgery.
Diagnostic laparotomy is required if a biopsy is needed for tissue analysis.

The procedures are therapeutic, with the help of which nephrectomy can be performed. For getting accurate diagnosis a biopsy performed using fine-needle aspiration is required. The method has limitations because it does not allow visualization of various morphological areas of the tumor. The tissues are sent to the laboratory for histological examination.

Examination of a biopsy specimen under a microscope is considered the gold standard in determining final diagnosis. Evaluation using hematoxylin and eosin staining is used. Immunohistochemical and molecular testing is sometimes performed.

Differential diagnosis helps distinguish lipomas from other types of tumors:

angiolipoma;
atypical lipomatosis of the retroperitoneum;
liposarcoma.

The choice of examination method remains at the discretion of the attending physician. You need to take the problem seriously and undergo regular examinations. It is extremely difficult to predict how long a lipoma will take to grow.

Many diseases can have similar signs and symptoms, so it is necessary to be examined and treated. It is impossible to prevent the formation of lipoma. Regular examinations help detect tumors early. It is believed that overweight and metabolic disorders provoke the appearance of wen.

Complications of kidney lipoma are primarily associated with fear of cancerous tumors. Only a biopsy can help determine how serious the tumor is. Surgery rarely complicated by damage to muscles, vital nerves and blood vessels. There is a risk of postoperative suture infections.

Research shows that kidney lipoma rarely develops into malignant pathologies. Most asymptomatic tumors are not removed after confirmation of their benign nature.

Doctors choose a wait-and-see approach for small lesions and perform a fine-needle biopsy. Surgical intervention with complete excision cures the disease and reduces the likelihood of relapse.

Surgical methods for treating lipoma are varied:

endoscopic surgery;
organ-conserving surgery;
partial or complete nephrectomy;
Tumor embolization involves the use of coagulation of the vessels feeding the lipoma.

There are several types of fatty tumors with the inclusion of cellular components: angiolipomas with vascular tissues, myelolipomas with muscle ones. Scientists conducted an experiment on differential diagnosis using ultrasound (ultrasound examination). The formations are distinguished by an extremely dense hyperechoic signal. The detection of diffuse hamartomas is associated with the development of tuberous sclerosis. The peculiarity of echogenicity is associated with adipose tissue and allows for accurate preoperative diagnosis of benign formations. Confirmation of angiolipoma using ultrasound allows prescribing conservative therapy and maintain a functioning kidney.

CHROMAFFFIN CELLS CHROMAFFFIN CELLS

(from chrome... and lat. affinis - related), adrenal cells, endocrine cells in the body of vertebrates, forming clusters (paraganglia) in different parts of the body, especially near the nerve ganglia. X. to. are produced and released into the blood. arr. catecholamines (adrenaline, norepinephrine, etc.). They are capable of precipitating chromium salts and, after fixation with them, acquire a dark brown color (hence the name). The largest accumulation of X. to. is the adrenal medulla. The totality of the blood cells of the body makes up the adrenal system. During embryogenesis, X. cells develop from the neuroectoderm.

.(Source: “Biological Encyclopedic Dictionary.” Editor-in-chief M. S. Gilyarov; Editorial Board: A. A. Babaev, G. G. Vinberg, G. A. Zavarzin and others - 2nd ed., corrected - M.: Sov. Encyclopedia, 1986.)

See what "CHROMAFFIN CELLS" are in other dictionaries:

- (from Greek chroma color and Latin affinis related) constitute the adrenal medulla in vertebrates and humans. They are also present in the plexuses and ganglia of the sympathetic nervous system. They produce the hormones adrenaline, norepinephrine, etc... Big encyclopedic Dictionary

Chromaffin cell (synonyms: pheochromic cell, pheochromocyte) is a neuroendocrine cell of the adrenal medulla and paraganglia. The embryonic source of chromaffin cells is the neural crest. The name comes from the words “chrome” and ... ... Wikipedia

- (from the Greek chrōma color and the Latin affinis related), constitute the adrenal medulla in vertebrates and humans. They are also present in the plexuses and ganglia of the sympathetic nervous system. They produce the hormones adrenaline, norepinephrine... ... encyclopedic Dictionary

- (from Chromo... and lat. affinis related) adrenal cells, intrasecretory cells in the body of humans and vertebrates, producing and releasing adrenaline, norepinephrine and, probably, a number of other catecholamines into the blood (See... ...

- (from the Greek chroma color and the Latin affinis related), constitute the medulla in the adrenal glands in vertebrates and humans. They are also present in the plexuses and ganglia of the sympathetic nerve. systems. They produce the hormones adrenaline, norepinephrine, etc... Natural science. encyclopedic Dictionary

enteroendocrine cells- enteroendocrine cells, isolated intraepithelial cells that are found in the glandular part of the stomach (gastric endocrinocytes), throughout the intestine (intestinal endocrinocytes), partially in the gall bladder, in general... ... Veterinary encyclopedic dictionary

CHROMAFFIN SYSTEM- CHROMAFFIN SYSTEM, chromaffin organs, adrenal system, chromaffin organ system, the name given, according to Cohn’s proposal, to a number of organs that selectively react by changing color, etc., to the action of chromium in its saline solutions. At …

ADRENAL GLANDS- (glandulae suprarena les, epinephra, hypernephra, paraganglia), paired endocrine organs lying in the posterior upper part of the abdominal cavity on the upper internal surface of the kidneys. The discovery and first description of the adrenal glands is attributed to the anatomist... ... Great Medical Encyclopedia

PHEOCHROMOCYTOMA- honey Pheochromocytoma is benign or malignant tumor, consisting of chromaffin cells that synthesize catecholamines. Chromaffin cells are localized mainly in the adrenal medulla (90% of cases), but they are also found in... ... Directory of diseases

Organs of animals and humans that produce and secrete specific substances usually involved in the physiological functions of the body. Some fluids secrete their products onto the surface of the body or mucous membranes through the excretory... ... Great Soviet Encyclopedia

Chromaffin cells (from Chromo... and lat. affinis - related)

adrenal cells, intrasecretory cells in the body of humans and vertebrates that produce and release into the blood Adrenaline, Norepinephrine and, probably, a number of other catecholamines (See Catecholamines) , contained in cytoplasmic granules. Originate from neuroectoderm. After fixation with chromium salts, they acquire a dark brown color (hence the name). The totality of the body's blood cells makes up the adrenal system (See Adrenal system) . In humans and higher vertebrates, chromiums have polygonal or irregular shape, sometimes with barely noticeable processes, are intertwined with capillaries and form clusters - paraganglia - in different parts of the body (near the nerve ganglia and fibers, in the area of cervicothoracic vessels, in the parenchyma of organs). The largest accumulation of cholesterol is the adrenal medulla (See Adrenal glands) . The production of neurohormones, accompanied by their release from cytoplasmic granules into the blood, is regulated by nervous mechanisms. In lower vertebrates, the blood cells have a multi-processed shape and are diffusely distributed in the walls of the large main vessels of the body and in the thickness of the heart muscle; The release of hormones from cytoplasmic granules occurs continuously. Chronic acids are also found in invertebrates, for example, in the ganglia of the ventral nerve chain in annelids.

N. A. Smitten.

Great Soviet Encyclopedia. - M.: Soviet Encyclopedia. 1969-1978 .

See what “Chromaffin cells” are in other dictionaries:

- (from chrome... and lat. affinis related), adrenal cells, endocrine cells in the body of vertebrates, forming clusters (paraganglia) in different parts of the body, especially near the nerve ganglia. X. to. are produced and released into the blood. arr.... ... Biological encyclopedic dictionary

PHEOCHROMOCYTOMA- honey Pheochromocytoma is a benign or malignant tumor consisting of chromaffin cells that synthesize catecholamines. Chromaffin cells are localized mainly in the adrenal medulla (90% of cases), but they are also found in... ... Directory of diseases

Chromaffin tissue gets its name from the ability of its cells to be stained with chromium salts. The second name of these cells - pheochromic - is associated with the color in which they are painted during this reaction (from the Greek phaios - brown).

This staining reaction, or Henle reaction, was first obtained by V. A. Betz in 1864 on cells of the adrenal medulla, which is the largest and most studied accumulation of chromaffin tissue.

The Henle reaction is by its nature a reduction reaction of chromium oxides. It is believed to be associated with strong reducing substances, possibly adrenaline and norepinephrine, produced by chromaffin cells. The reaction with chromium oxides is nonspecific for adrenaline and norepinephrine and can be obtained under the influence of reducing agents such as ascorbic acid, sodium bisulfate, hydroquinone, aniline, resorcinol.

Chromaffin cells develop from sympathoblasts of the ganglion plate, i.e., they are of neuroectodermal origin. Sympathetic postganglionic neurons also develop from sympathoblasts. Thus, chromaffin tissue cells have a common origin with cells sympathetic division nervous system.

Adrenal medulla. The adrenal gland, described for the first time in 1564 by Eustachius, is paired organ, which is located above the upper pole of the kidney and is closely connected with it, being enclosed in a duplication formed by the anterior layer of the fascial capsule of the kidney. G. A. Corning indicates that the right adrenal gland is a triangular pyramid and lies in the form of a cap on the upper pole of the kidney, and the left one has the shape of a crescent and is adjacent to the anterior and medial edge of the kidney. Projection of the adrenal glands, located at the level of the XI and XII thoracic vertebrae, onto the anterior abdominal wall corresponds to the epigastric region, partially to the right and left hypochondrium. Covered with peritoneum in the lower part of the anterior surface, the right adrenal gland is in front and outside adjacent to the right lobe of the liver, behind - to the diaphragm, its medial edge faces the inferior vena cava. The left adrenal gland, usually located below the right, is covered with peritoneum in the upper part of the anterior surface and outside, and is adjacent to the diaphragm behind and medially. Its lower edge reaches the tail of the pancreas and the vessels of the spleen. The anterior surface of the left adrenal gland faces the stomach. The semilunar nodes of the solar plexus are medially adjacent to both adrenal glands.

The size and weight of the adrenal glands depend on age and various factors(pregnancy, fatigue, cold and other effects). On average, in an adult, the weight of both adrenal glands is 7-20 g with a height of 30-60 mm, a width of 20-30 mm and a thickness of 4-9 mm.

During embryogenesis, the adrenal glands appear much later than the liver and heart. As N.V. Popova-Latkina points out, the earliest development of the adrenal glands is found in an embryo 9 mm long. Initially, the adrenal glands consist of a single interrenal tissue of mesodermal origin, developing into the adrenal cortex. In embryos 13-15 mm in length, neuroblasts, cells of the neural ganglion plate of ectodermal origin, begin to migrate into this epithelial adrenal gland. The movement of neuroblasts occurs along the internodal branches of the sympathetic trunk from the thoracic and upper lumbar nodes. N.V. Popova-Latkina notes that in embryos at the beginning of the 3rd month, sympathetic fibers, together with migrating and developing cells (sympatho- and chromaffinoblasts), form, as it were, the root of the adrenal gland, forming its medulla.

The adrenal gland has two layers - the outer, cortical, and the inner, medulla.

D. M. Golub distinguishes three stages of differentiation of the adrenal medulla. During the first stage (in an embryo 20 mm long), sympathoblasts transform into chromaffinoblasts, which are not yet stained with chromium. In the second stage (embryo 40-48 mm in length), prochromaffin cells are formed, which are an intermediate form between chromaffinoblasts and pheochromocytes. Only at the third stage do chromaffin cells become stained with chromium salts. G. A. Lyalina detected signs of chromaffinity of brain cells in a 3-month-old fetus. The medulla forms a narrow strip in the center of the adrenal gland, which is surrounded on all sides by cortical tissue. By the time the fetus is born, it is not yet fully developed, although there are signs of secretion.

On section, the adrenal medulla is pinkish in color, about 4 mm thick and consists of fairly large epithelial cells of various shapes, with large nuclei located centrally or eccentrically, and light protoplasm. In the cells you can see the cell center, the Golgi apparatus, mitochondria, and chromaffin granules.

Policard and Boud consider chromaffin granules to be the central functional element of the adrenal medulla. Under electron microscopy, the granules have a minimal diameter, are structureless, make up approximately a third of the weight of the cells, contain up to 35-40% of the total weight of cytoplasmic proteins, more than half of phospholipids and 38% of medulla cholesterol. Approximately 4.3% of the wet weight of the granules and 19% of their dry weight are catecholamines. The latter are released from the granules under various experimental influences - in an acidic and hypotonic environment, during freezing and increasing temperature, etc. After the adrenal glands are released from adrenaline, the medulla contains the same number of granules as before the exposure.

Study of granules in ultrathin sections of the adrenal glands using electron microscope found that they are compact and homogeneous, surrounded by thin membranes. Other granules do not have such density and homogeneity - throughout their entire body or only at the edges, a mesh grain pattern is observed, consisting of small (about 175 angstroms in diameter) grains located at a distance of approximately 250 angstroms from each other.

The granularity of the cells of the medulla can produce staining, in addition to chromium salts, with iron sesquichloride, salts, and silver nitrate.

In some cells no granules are found. This serves as one of the reasons for distinguishing two types of cells in the adrenal medulla.

Using various histochemical methods, two types of cells of the adrenal medulla have been isolated - some of them are capable of producing adrenaline, and others - only norepinephrine.

Kracht found that the nuclear surface of adrenaline-containing cells is on average 30% smaller than the surface of the nuclei of cells containing norepinephrine.

The cells of the medulla form cords located near the vessels. The connective tissue base of the medulla, which contains collagen, argyrophilic and elastic fibers, is closely connected with the walls of blood vessels, in particular veins.

The medulla and cortical layers of the adrenal gland, having different origins, structures and physiological significance, but united in the process of evolution into single body, have a common thin fibrous capsule and a common blood supply.

Many small blood vessels (up to 50) approach the adrenal gland from all sides. The smallest number of vessels approaches from the lateral side. The right adrenal gland receives slightly more branches than the left. E.I. Tarakanov, together with E.P. Pospelova, divided the blood supply to the adrenal glands into 6 sections: from the inferior phrenic artery, from the aorta, from the renal artery, from the celiac artery, the artery of the renal capsule and from the artery of the posterior surface of the adrenal gland.

The abundant vascular network intensively supplies the adrenal gland with blood: per 1 g of their weight per minute there is 7 ml of blood.

All vessels of the adrenal capsule anastomose, forming a network from which capillaries arise that feed the adrenal tissue. The blood supply to the medulla is carried out through the so-called perforating vessels, which depart from the superficial network and pass through the cortex without giving branches. In addition, the medulla receives blood from the vessels of the cortex. Venous network the medulla sharply predominates in number over the arteries. The venous capillaries of the medulla begin among the cells of the reticular zone of the cortex, pass into the sinusoids, or venous sinuses, and then merge into venules and, finally, into the central vein of the adrenal gland. The central vein of the adrenal gland is distinguished by a number of features: it is wide, has a thick wall, which contains well-developed muscles, consisting of circular and longitudinal layers; does not have valves. According to E.I. Tarakanov, the features of its structure allow reverse blood flow at certain physiological conditions. As the observations of Heinvaar and M.R. Sapin showed, the muscular layers of the central vein can act as an outflow regulator venous blood containing adrenal hormones. M.R. Sapin notes that in hypertension, the muscle layers are much more developed than normal, and this can limit the outflow of blood (and hence the release of hormones) into the inferior vena cava. Perhaps this increases the outflow of blood through another venous route - through the veins that perforate the adrenal capsule into the portal system.

Almost every cell of the medulla, as established by M.R. Sapin, has contact with lymphatic capillaries, which form a network according to the structure of the medulla - cell groups, connective tissue, blood vessels. The outflow of lymph occurs through the drainage lymphatic vessels along blood vessels into regional The lymph nodes, the role of which for the right adrenal gland is performed by the preaortic, inter-aortocaval, retrocaval, laterocaval and precaval nodes, and for the left adrenal gland - by the preaortic and left lateroaortic lymph nodes.

Extra-adrenal chromaffin tissue. In addition to the adrenal medulla, chromaffin cells are also present in a number of other areas in the form of more or less large clusters. These include the following formations.

Paraganglia. They are round, small in size (1-3 mm in diameter) formations found in the capsules or near the nodes of the sympathetic nervous system. Most of the paraganglia are located near the solar, renal, adrenal, aortic and hypogastric plexuses.

Chain of chromaffin tissue, described by Cohn, is located anterior to the abdominal aorta and above the inferior mesenteric artery.

The organs of Zuckerkandl are located on both sides of the aorta at the origin of the inferior mesenteric artery.

In the prenatal period and early childhood these formations, reaching sizes of 10-12 mm, are the main accumulation of chromaffin tissue and perform its functions. However, when the adrenal medulla becomes the main functioning part of the chromaffin system, these organs quickly undergo reverse development and are usually microscopic in size in adults.

Individual chromaffin cells are also scattered in the skin and in the myocardium.

Previously, the carotid gland located at the bifurcation of the common carotid artery was considered a chromaffin formation. As further studies have shown, the tissue of this gland is not true chromaffin tissue, does not give a typical staining reaction and does not produce catecholamines.

The presence of chromaffin formations outside the adrenal gland is important to remember, since tumors of chromaffin tissue can originate not only from the adrenal glands, but also from these formations. This circumstance is of great practical significance for topical diagnosis of chromaffin tumors.

Additional adrenal glands. Back in the 19th century, it was discovered that along with the main adrenal glands, there are sometimes additional ones. Various authors have found these formations in the hilum and in the tissue of the kidneys, in the ligaments of the uterus, in the ovaries, near the epididymis, along the seminal vessels, near the inferior vena cava, etc. When the main adrenal glands are removed, they can hypertrophy. Cases of tumors developing from these formations have also been described.

Accessory adrenal glands, as a rule, are formed by the cortex, and extremely rarely they contain elements of the medulla. Chromaffin tumors from these formations are practically not found.