BCG-induced changes in size of thymic cortex and thymus-dependent areas in spleen and lymph nodes of mice.

Significant changes in the size of thymic cortex and of thymus-dependent areas (TDA) in spleen and lymph nodes, were revealed by histomorphometry after intraperitoneal injection of BCG into young-adult BALB/c mice. Reactions of the thymic cortex were found to be biphasic with initial involution and subsequent hyperplasia. TDA in the spleen showed a transient involution with almost complete regeneration at the end of the experiment. The response of TDA in lymph nodes was characterized by pronounced and persistent hyperplasia. The functional significance of these BCG-induced changes of lymphoid tissue compartments is discussed.