Special structural and microstructural changes in thymus in «catabolic» phase after experimental hyperthermia

The aim of the research was to study thymus cellular composition in 45 Vistar rats after their exposure to a singular course of experimental hyperthermia (EH) leading to thermoplegia. At different stages of the experiment (5 hours, 3 days after EH) the trial rats were euthanized under light narcosis for the purpose of subsequent extraction of thymus for further research. Histolic specimens were produced according to standard methods. Immunoblasts were differentiated in all zone of thymus. Avarage and small-size lymphocytes, cells with mitosis shapes, cells with pyknotic nuclei, epithelial cells, and macrophages (1000 times expansion on the standart area 4500 mkmI) were indetified in all areas of thymus as well. It has been established that the influence of the EH on the rat’s organism leads to the accidental involution of thymus. The Involution of thymus corresponds to the «catabolic» phase of the posthyperthermal period (5 hours, 3 days after EH), which was expressed in relative weight decrease of the organ (25 %), reduction of the relative cortex area (15 %) and decrease in lymphocyte density (12 %). Enhancement of destructive process on tissue levels was revealed. Manifistations of perivascular hypostasis, migration of cellular elements in lymphatic spaces and capillaries were noted.