Distribution of dividing thymocytes in rat thymic cortex during daily cycle.

: In the present study, frequency of thymocyte divisions was analyzed in the rat thymic cortex, as related to (1) distance from thymic capsule and (2) the daily cycle. Frequency of thymocyte divisions was estimated in successive 10 micron(s) thick layers of the cortex. An evident daily cycle was detected in the thymic cortex with increase in the number of cell divisions around 8 pm.