FEATURES OF THE ULTRAMICROSCOPIC STRUCTURE OF THE PARATHYROID GLANDS IN MATURE RATS AFTER IMMUNOSUPPRESSION

The structure of the parathyroid glands actively responds to the action of various exogenous factors, but information about morphological features of the structure of the organ during immune status changing is limited.The objective of the work was to study features of electron-microscopic structure of the rat parathyroid glands under immunosuppression caused by the administration of cyclophosphamide. The study was carried out on 24 male rats of reproductive age with initial body weight 180 ± 10 g. Maintenance and care of animals conducted in accordance with the norms of bioethics. The animals received an intramuscular injection of cyclophosphamide at a dose of 200 mg/kg. The animals were sacrificed on the 3rd and 30th day after the given injection. We studied the ultrastructure of the rats’ parathyroid glands in norm as well as after immunosuppression. The parenchyma of the parathyroid glands of intact animals consisted of two types of cells: chief cells and oxyphil cells. The ultrastructure of parathyroid chief cells and the mode of secretion were typical to other polypeptide-secreting endocrine cells. Those features correlated with the cells functional activity. The polyhedral, slightly eosinophilic chief cells were more numerous and formed irregular, anastomosing cords supported by delicate connective tissue. Oxyphils, which appeared after the first decade of life, were larger, more acidophilic cells that were irregularly distributed and occurred singly or in clumps. Using electron microscopy we detected that oxyphils were packed with mitochondria but, unlike chief cells, they lacked secretory vesicles; they are thought to be nonsecretory. Fat cells were also found in the parenchyma.The introduction of cyclophosphamide into the rat’s organism at high doses caused certain changes in the ultrastructure of the organ. We observed polymorphism of cell nuclei; reduction in the diameter of the vessels of the microcirculation; reduction in the number of secretory granules; increase in the number of lipid and colloid droplets in the cell cytoplasm on 3rd day. We noticed tendency to normalization of morphological structure of the organ after the administration of cyclophosphamide on the 30th day.