[Duration of mitosis in mouse thymus cortex cells under normal conditions and after antigen administration at different times of the day].

The influence of an antigen injected at different periods of the circadian mitotic activity on the cell proliferation in the thymus cortex was studied. The duration of mitosis and the number of cells entering division were determined. A pronounced stimulating effect of immunization with sheep red blood cells entering mitosis increased, while the duration of mitosis diminished (colchamine mitotic index was 29.79 percent in control mice, and 47.99 percent in the immunized ones. The duration of mitosis was 0.4 hours in control animals, and 0.24 hours in the immunized ones. When compared with intact mice, the animals immunized in the evening showed no significant changes in the parameters studied.