Few people know that on the kidneys on top there is an “attached” organ called the adrenal gland. The adrenal gland secretes a number of hormones into the bloodstream (adrenaline, norepinephrine, cortisol, aldosterone, sex hormones). Therefore, with problems with the level of certain hormones, first of all, attention is paid to the adrenal glands. With tumor or cystic neoplasms of the adrenal gland, it is examined histologically. We will talk about him in this article.
Where is the organ located
The organ is located on top of the kidneys. Since there are two kidneys, there are also two adrenal glands. The adrenal gland in shape resembles a pyramid, volumetric shape with rounded edges and small size. The right adrenal gland is in contact with the liver (with its visceral surface) from above and in front, and behind the diaphragm. The left adrenal gland is in contact with the pancreas from above and in front, and the diaphragm is behind the left adrenal gland.
It synthesizes a number of hormones fundamentally important for the body, such as cortisol, adrenaline, norepinephrine, dopamine, gluco- and mineralocorticoids, as well as sex hormones.
The structure and functions of the adrenal glands, histology
In order to understand what histology is (as a diagnostic method), you need to have an idea of what a histological preparation is and how it is prepared.
A piece of the organ is taken, a slice is cut from it (a very thin fragment, which is several microns in thickness). Then this slice is stained with special dyes, after which the preparation is ready. And he is examined under a microscope.
Analysis of histology of the adrenal gland occurs in several stages:
- Inspection of the fat, near-faceted capsule.
- Inspection of the stroma of the organ.
- Inspection of the parenchyma.
- Inspection of the brain.
Near-capsule
Examining the near-organ capsule, you can see that it consists mainly of adipose tissue, which on the preparation is colored yellowish-white. Large rounded formations are visible in the capsule. In the middle of these formations there are many oval-shaped cells. To consider these cells in more detail, it is necessary to switch to a large increase.
Moving to a large increase, you can see the nervous tissue. The nuclei of the cells are large and bright. The nucleus itself in the cell is eccentric. Since the cells are stained in bright colors, it can be argued that they contain euchromatin. Between the cells there are many small cells - microglia. Nearby is a nerve fiber, which consists of elongated cells - oleocytes (Schwanowski cells).
Based on the foregoing, we can draw the following conclusion: large roundish formations in the periorgan capsule are the parasympathetic perior organ ganglion and the nerve itself.
It is worth noting that in addition to nerve fibers in the near-organ capsule there are many adipocytes - adipose tissue cells. Many veins and arteries pass through the thickness of adipose tissue. Between themselves, they differ in a layer of muscle tissue. In an artery, it is significantly larger.
Organ stroma
Before moving on to the stroma, I would like to say: the adrenal gland is a typical parenchymal organ, which consists of the stroma and parenchyma.
The elements of the stroma include:
- Connective tissue capsule. It consists of two layers. From a layer of fibers, which are represented by dense unformed connective tissue. And from the cell layer, from which the formation of the organ parenchyma begins.
- Interlayers of loose connective tissue that extend to the medulla.
Organ parenchyma
It is represented by three layers. The top layer is glomerular. Between the so-called glomeruli there are gaps that are painted white. These spaces are called sinusoidal capillaries.
Since, as they go deeper into the organ, the epithelial cords change somewhat and become more ordered, they begin to resemble bundles. Therefore, the second layer of the adrenal cortex is called bundle.
The third layer of the cortex on the histology of the adrenal gland is mesh. Why is he called that? Because the epithelial cords in this layer are intertwined and form the so-called network.
Under the mesh layer of the adrenal cortex is a thin layer. This layer consists of loose fibrous tissue. Separates cortical from brain.
Adrenal medulla
On the histology of the adrenal gland, its brain substance is no longer represented by epithelial cords, but by endocrine cells - chromophinocytes. These are cells of a nervous nature. Since the histology of adrenal gland development has shown that these cells are formed from nerve tissue (neuroectoderm). There are many spaces in the brain - these are all the same sinusoidal capillaries.
It is worth noting that the brain substance secretes hormones much more actively and is therefore much more penetrated by blood vessels. The endothelial lining is visible in the vessels.
Where are some hormones produced?
On the adrenal gland histology preparation, you can see where the hormone production is disturbed, but you need to know the relevant areas. In the glomerular zone of the adrenal cortex, the following are produced:
- Aldosterone - normalizes the balance of sodium and potassium in the body. During its synthesis, sodium reabsorption increases, and potassium decreases.
- Corticosterone - has insignificant mineralcorticoid activity.
The beam zone produces hormones such as cortisone and cortisol. They increase the excitability of nerve tissue, activate lipolysis to glucose. In addition, they play an important role in inflammatory processes, inhibiting them. Participate in immune responses and allergic reactions.
The mesh zone produces androgens, sex hormones. These hormones affect secondary sexual characteristics.
The brain substance is catecholamines such as adrenaline and norepinephrine. Affect the metabolic rate, the speed of nerve impulses. The hormone adrenaline is the main activator of the body in stressful situations.