ULTRASTRUCTURAL FEATURES OF NEURO-GLIAL-CAPILLARY RELATIONSHIPS OF THE HIPPOCAMPAL CA3 AREA ON THE 21st DAY AFTER EXPERIMENTAL THERMAL INJURY

Abstract

Severe thermal injury leads to a number of morphofunctional changes that occur in violation of integrity or loss of skin in deep burns and endogenous intoxication on the background of which significant structural and metabolic disorders in all organs and systems of the affected organism are developed. This is manifested in a complicated symptom complex of burn disease. Changes in the central nervous system play an important role in the pathogenesis of burn injury, the nature and depth of morphofunctional changes in individual cerebral structures, in particular in the hippocampus (central organ of the limbic system, which is especially sensitive to various pathogens), after thermal lesions remain poorly studied. The aim of our study was to establish the features of submicroscopic changes in the structural components of the hippocampus after 21 days under conditions of experimental thermal injury. The experimental study was performed on white laboratory male rats. Third-degree burns were applied under thiopental-sodium anesthesia with copper plates heated in boiled water to a temperature of 97–100°C. The size of the affected area was 18–20% of the rats’ body epilated surface. Histological changes were studied on the 21st day from the beginning of the experiment. For electron microscopy, the obtained ultrathin sections were contrasted with uranyl acetate and lead citrate according to the Reynolds method. It was found that on the 21st day after the experimental thermal injury significant alternative changes in neurons, glial cells and the microcirculatory tract of the hippocampus were defined which developed on the background of excessive endogenous intoxication. Neurons are hypochromic and sharply hyperchromic, disorganized and have an altered shape; there are cell-free areas. Endoplasmic reticulum, Golgi complex, mitochondria are destructively changed. Degeneration of macroglial cells has been noticed. Their nuclei are high in electron density in which heterochromatin predominates. Destruction and lysis of organelles, lysosomes have also been found in the cytoplasm. These changes of astrocytic glia lead to impaired trophic function and the relation between astrocytes and blood capillaries. Hemocapillaries wall remodeling is manifested by the total edema, compaction of the basement membrane. The lumenal surface of the plasmolemma of endothelial cells is homogeneous, indistinctly contoured. The cytoplasm of endothelial cells is swollen, enlightened, and poor in organelles; there is a small number of micropinocytic bubbles and vesicles.