The pineal gland
Endocrinology / / August 12, 2017
E pifiz (epiphysis cerebri) - upper appendage of the brain, or the pineal gland (glandula pinealis), known at least for the past 2000 years.However, a careful study of the pineal gland was launched only in the XIX century.The first studies were devoted to comparative anatomy and histology of the prostate.
In 1910 Pellizi described two cases of early sexual and physical development of boys and suggested pineal origin of this syndrome.Later similar disease has been described by other authors.Have died from the syndrome of people are often embryonic tumor of the pineal gland.Clinical observations do not seem to leave no doubt that the pineal gland affects the sexual and physical development of a person.However, numerous experiments with removal of the prostate or did not work at all, or resulted in contradictory results, which apparently can be explained by the complexity of the surgical approaches, damage to surrounding tissue during operations and the development of fatal bleeding after surgery.
Only in 1912 was the first to Foa in experiments on chickens show that the pineal gland has an inhibiting effect on the processes of growth and sexual development.
embryogenesis, anatomy and histology
epiphysis concerns, like posterior lobe of the pituitary to the midbrain.In humans, it occurs on the second month of fetal life from the caudal end of the roof of the midbrain as eversion ependyma.Further transformation of the body are reduced to a thickening of its walls, the disappearance of the lumen, the penetration of the mesoderm cells together with the blood vessels.
Pineal gland is located deep under the mid-plane of the cerebral hemispheres.The top of his laid back, and it lies in the furrow between the superior colliculus.Base gland directed anteriorly and by the short leg abuts the rear of the third ventricle.Along the foot of the gland stretching on both sides of two white beam (habenula).Last connected with the thalamus.III ventricle cavity forms a small protrusion at the base of the epiphysis (recessus pinealis), representing the balance of the original germ of the lumen of the pineal gland.
pineal gland (glandula pinealis) (horizontal section of the brain with respect to X. H. Hodos).
1 - glandula pinealis;
epiphysis form a human constant.In newborns and in early years of the life of the iron body is circular, and in adults - ovoid, flattened in a downward direction, while the side surface of 4-5 mm and 2-3 mm in thickness.Front and top
epiphysis is covered with the rear segment of the choroidal membrane III ventricle, behind and below - the pia mater.From delicate connective tissue sheath surrounding the pineal gland, fade into the layer separating the parenchyma of the organ from the sensible to the segments, different in shape and size.Parenchyma gland consists of a light-rich cytoplasm of cells with a large nucleus (pineal chief cells) and small dark nucleus and a narrow rim of protoplasm cells.In the cytoplasm the main cells of the pineal gland is found the smallest acidophilic and basophilic stippling (isledovateli many see it as a proof of endocrine activity of the pineal gland).In addition, the major pineal cell protoplasm rich in lipoid and pigment inclusions.It is believed that the pineal parenchyma cells derived from glial cells, the smaller cells are young, capable of differentiating into the main.It is now considered a proven presence in the pineal gland of the nerve cells.
source of blood supply to the prostate artery is derived from the two systems: the internal carotid and the basilar artery.On quadrigemina surface a dense arterial network around the pineal gland, which is in the thick of the glands penetrate the connective tissue sheath of 6 to 10 branches.Vnutrizhelezistoe vascular bed in children is fine and srednepetlisty character.Epiphysis rich blood supply, despite the small size body, according morphologists suggests its functional activity.The pineal gland has a dual innervation - the central and sympathetic.Most nerve fibers derived from taeniae thalami and habenulae knots they tie the epiphysis with the midbrain.Sympathetic fibers originate from ganglion conarii.Proceedings of nerve fibers within the prostate has not been studied: some believe that the nerve fibers ramify around cancer cells, while others argue that they end perivascular.
Most researchers who have studied age-related features of the pineal gland, according to her body undergoing relatively early involution.Therefore pineal gland is called early childhood.With age, the pineal gland in the observed growth of connective tissue, reducing the amount of parenchyma cells, depletion of body vessels.These changes in the human pineal gland begin to show from 4-5 years of age.After 8 years in the iron, there are signs of calcification, lead to the deposition of the so-called "brain sand» (acervulus cerebri).According to Kitay and Altschule, based on the statistical processing of large composite material, deposition of cerebral sand in the first decade of life occurs between 0 and 5%, the second - from 11 to 60%, and in the fifth reaches 58-75%.Brain sand consists of organic matrix, permeated with carbon and calcium phosphate, and magnesium.Along with age restructuring gland parenchyma changes and its vasculature.Melkopetlistaya rich arterial anastomosis network characteristic of the epiphysis of the newborn, with age is replaced by longitudinal, slightly branching arteries.In the adult pineal gland artery take the form of elongated along the length of highways.
started in the 4-8 age involution of the pineal gland in the future progresses, however, the individual cells of the parenchyma of the pineal gland are saved to a ripe old age.
revealed by histological examination of the signs of the secretory activity of the pineal gland cells are found in the second half of fetal life.In adolescence, despite the sharp reduction in the size of the parenchyma of the pineal gland, pineal secretory function of the main cells does not stop, as evidenced by the presence in their cytoplasm of large vacuoles, which are located on the periphery of the cell, granules, and the phenomenon of decay of nuclei (Holocrine secretion).
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Now for studying intracellular synthetic and metabolic processes have been successfully applied histochemical methods.It is proved that the growing, multiplying and secreting cells contain a protein secretion, as a rule, a large number of nucleo-proteids.Wislocki epiphysis and Dempsey in monkeys, a Mikami glands in goats, sheep and other animals found by histochemical methods at a significant content of ribonucleic pineal cell cytoplasm and in nuclei - deoxyribonucleic kisloty.V assessing the ability of cells to a specific activity of great importance is attached to their content ofenzymes involved in both the internal cellular metabolism and in the manifestation of cell functions.One such enzyme is alkaline phosphatase.The presence of this enzyme by the above authors found in the cytoplasm and nuclei of cells of various animals epiphysis.In addition, pineal cell cytoplasm glycogen detected, which also characterizes the functional activity of the cells.The results of histochemical studies show an active exchange processes in the cells of the pineal gland and indirectly support the hypothesis of their specialized functions.In support of this hypothesis say and observe the absorption of radioactive substances epiphysis.It is proved that the pineal gland, cats, guinea pigs and other animals absorbs radioactive phosphorus (32P) is three times greater than the cerebellum, and radioactive iodine (J131) is included in the pineal gland in greater numbers than any other organ, with the exception of the thyroid gland.
Such substances physiologically important as histamine, acetylcholine, noradrenaline and serotonin, are found in the pineal gland in large quantities than other parts of the brain.It is proved that the pineal gland is formed neurohormone - melatonin.The role of this substance in humans has not yet been elucidated.In mice, as shown by Cohen et al., Melatonin suppressing ovarian function.
Thus, the features of embryogenesis detected histologically phenomenon secretion of histochemical studies as well as monitor the absorption of the pineal gland of radioactive substances show that it is impossible pineal considered vestigial organ, deprived of functional value, at least in the growing organism.