The total and differential Cell counts of femoral bone marrow and peripheral reticulocyte counts were determined in male ddY mice up to day 11 after an intraperitoneal injection of 2 mg/kg of mitomycin C. 1. Total marrow cell counts showed a minimum value on day 2 after the injection, and then recovered to the control level on day 7. 2. In the differential cell counts, the minimum values were observed on day 1 for proerythroblasts and basophilic erythroblasts, on day 2 for polychromatic erythroblasts, and on day 4 for mature neutrophils. Recovery was seen from the 4th to 7th days after injection. Marrow lymphocytes showed a maximum value when the total counts were minimum. 3. The peripheral reticulocytes almost disappeared 4 days after the injection, and recovered to the pretreatment level on day 11.
