The effects of cyclophosphamide, azathioprine, and 6-mercaptopurine on oocyte and follicle number in C57BL/6N mice.

Cyclophosphamide, azathioprine and 6-mercaptopurine were studied for oocyte and follicle toxicity in a murine ovarian toxicity assay system. Seven days after a single treatment with cyclophosphamide (100 mg/kg ip), 63% of the primordial follicles and 0% of the growing or large follicles and their oocytes were destroyed in four week old C57BL/6N mice. Treatment with azathioprine (100 mg/kg/day ip x 9 days) or 6-mercaptopurine (100 mg/kg/day ip x 9 days) suppressed weight gain and increased mortality but had no effect on the number of oocytes or follicles in these mice. These data are consistent with previous observations on the effects of cyclophosphamide, azathioprine and 6-mercaptopurine on human ovarian toxicity. This suggests that the murine ovarian toxicity assay system may be useful in evaluating xenobiotics, including drugs, for human ovarian toxicity.