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Main Title Antifertility Effect of Methoxychlor in Female Rats: Dose- and Time-Dependent Blockade of Pregnancy.
Author Cummings, A. M. ; Gray, L. E. ;
CORP Author Health Effects Research Lab., Research Triangle Park, NC.
Publisher c1989
Year Published 1989
Report Number EPA/600/J-89/050;
Stock Number PB90-100918
Additional Subjects Pesticides ; Animal physiology ; Fertility ; Toxicity ; Rats ; Reproductive system ; Estrogens ; Progesterone ; Uterus ; Reprints ; Methoxychlor ; Dose response relationships ; Ovum implantation ; Organ weight ; Corpus luteum
Library Call Number Additional Info Location Last
NTIS  PB90-100918 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 11p
Long-term exposure to methoxychlor (MXC), an estrogenic pesticide, produces infertility in rats, and short-term exposure blocks the decidual cell response. To address the short-term effects of MXC on fertility, the differential effects of MXC dosage and timing of administration (relative to implantation) on several gestational parameters were investigated. When MXC was administered during early pregnancy (Days 1-8), dose-dependent decline in implantations and uterine weight was seen with no effect on ovarian weight or corpora lutea; MXC reduced serum progesterone at all doses. Preimplantation administration of MXC (Days 1-3 of pregnancy) produced a decline in implantations and uterine weight, while post-implantation dosing (Days 4-8 of pregnancy) increased resorptions to 100%, decreased uterine weight, and reduced serum progesterone without affecting the number of implantations, ovarian weight, or number of corpora lutea. The data show that short-term MXC dosing during early pregnancy produces a dose-related infertility. The blockade of pregnancy by the preimplantation administration of MXC may be mediated by a direct effect on preimplantation uterine development. The fetal resorption seen following post-implantation dosing is considered a manifestation of both reduced serum progesterone and the direct disruption of normal decidual development by MXC. (Copyright (c) 1989 Academic Press, Inc.)