ULTRASTRUCTURE OF THE CAPILLARIES OF THE VASCULAR BODIES OF THE BRAIN IN THE CONTEXT OF THE DEVELOPMENT OF INTRACRANIAL HYPERTENSION

Intracranial hypertension is a frequently reported pathology of the brain. Its pathogenesis is based on hypersecretion of secretion and impaired reabsorption of cerebrospinal fluid (CSF). Its secretion is carried out due to vascular bodies (vascular plexuses), which are derivatives of its soft shell. According to their structure, they can be attributed to vascular epithelial organs. The production of cerebrospinal fluid depends on the functional activity of vascular bodies, which is primarily due to the structural and functional relationships between their epithelial cells and vessels of the microcirculatory bed. The main metabolic link of the latter is the capillaries at the level of which the bidirectional transport of substances (from tissues to the bloodstream and back) takes place]. Therefore, the intensity of metabolic processes occurring in vascular bodies during secretion of cerebrospinal fluid directly depends on the structure of the wall of their capillaries. Considering that the pathogenesis of intracranial hypertension is often based on hypersecretion of cerebrospinal fluid, as well as the inconsistency of the literature data concerning the structure of the microcirculatory bed of the vascular bodies of the brain, the task was set to establish the features of the ultrastructural organization of their capillaries. The study was carried out using the technique of electron microscopy. The ultrastructural organization of the capillaries of the vascular bodies of the lateral ventricles of the brain was chosen as the object. The material was fragments of tissues of the vascular bodies of the lateral ventricles of the brain of a domestic bull. The material was obtained during the planned slaughter of animals. Tissue samples were taken from five individuals aged 1.5 years who had no signs of damage to the nervous system. Their processing for the production of ultrathin sections was carried out according to generally accepted methods. The sections were contrasted with a 2.0% aqueous solution of uranyl acetate and a solution of lead citrate and studied on an electron microscope Jem-1011 (JEOL, Japan) at magnifications of 2500-3000. When designating cellular and non-cellular structures, terminology corresponding to the International Histological Nomenclature was used. It has been established that there are three types of capillaries in the villi of vascular bodies, which have features of their structural organization. At the same time, regardless of their morphological type, they are lined with fenestrated endothelium. There are no pericytes in the composition of the capillary wall of the first type. One layer of pericytes participates in the formation of the capillary wall of the second type. The walls of capillaries of the third type are characterized by the presence of a monolayer formed by several pericytes embedded in the cleavages of a thick basement membrane. The revealed ultrastructural features of the architectonics of the capillaries of the vascular bodies of the brain can serve as a comparative guideline in assessing their morphofunctional state, both normally and in the case of arterial hypertension of the brain.

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