DECREASED SUPEROVULATION IN ADULT MICE FOLLOWING NEONATAL EXPOSURES TO TECHNICAL METHOXYCHLOR

To examine the effects of technical methoxychlor (MXC) on superovulati on, neonatal mice received intraperitoneal (i.p.) injections of either sesame oil, 10 mu g of estradiol 17 beta, or 0.1, 0.5, or 1 mg of tec hnical MXC. At 2 and 4 months, half of the mice received a superovulat ory regimen of 10 IU pregnant mare's serum gonadotropin followed by 10 IU human chorionic gonadotropin. The mice were sacrificed 15 to 20 h later, the number of ovulated oocytes were counted, and the ovaries we re removed for histology, In the lowest MXC dose, the ovaries appeared normal and at 2 months, ovulated the same number of oocytes as contro ls, Estradiol or the highest two MXC doses induced ovarian atrophy. Fo llowing gonadotropin injections, these ovaries also ovulated oocytes, However, the number of oocytes recovered from experimental mice exhibi ted a time-and dose-dependent decline, and by 4 months, their number w as significantly reduced. Neonatal exposures to MXC reduces ovulatory rates and ovarian functions in adults. (C) 1997 Elsevier Science Inc.