[Age related morphological features of rat peripheral lymphoid organs at various levels of antigenic load]

Peripheral lymphoid organs from 2 different groups of laboratory rat's was studied (30 animals in each group). 1) Gnotobionts received from experimental - biological models Iffa-Credo laboratory (Lyon, France), 2) Ordinary conventional animals from the same laboratory, contained in standard conditions of vivarium microbial environment (control group). Animals from each group were subdivided into 2 aged categories (15 in each group): mature (8-12 month, 200,0 - 250,0 g) and aged (I period of old age 24-32 month; 300,0-450 g.) animals. Histological, electron-microscopic and morphmetric methods of studies were used. Correlations between morphological peculiarities and cellular composition of the rat's lymphoid tissue with antigenic load and age were determined. Namely, gnotobiont rat's lymphoid tissue contains less mature population, hence inactive lymphoid cells compared with conventional animals. However, with age this processes in both animal groups acquire a similar orientation.