Effect of "activated" cyclophosphamide on mouse oocyte in vitro fertilization and cleavage

To investigate the involvement of oocytes in the mechanism of chemotherapy-induced ovarian failure, ovulation was induced in mice using pregnant mares' serum gonadotropin and human chorionic gonadotropin. Oocytes (with cumulus) were incubated for 4 hours with "activated" cyclophosphamide, 4-hydroperoxycyclophosphamide (PCTX) at 0, 1, 10, 100, and 500 micrograms/mL. Oocytes were then washed, fertilized with sperm obtained from nontreated male proven breeders, and incubated for 4 days. "Activated" cyclophosphamide inhibited dissolution of the cumulus and reduced fertilization and early cleavage rates in a dose-related manner. The data demonstrate that exposure of oocytes to cyclophosphamide metabolites in vitro adversely affects oocyte function. Oocytes may be involved in the mechanism of cyclophosphamide-induced ovarian failure.