Effects of methoxychlor on the reproductive system of the adult female mouse. 1. Gross and histologic observations

Reprod Toxicol. 1991;5(2):139-47. doi: 10.1016/0890-6238(91)90042-e.


The purpose of this study is to examine the effects of the pesticide methoxychlor (MXC) on the reproductive system of the adult female mouse. Sexually mature (7- to 8-week) virgin female CD-1 mice were exposed to 1.25, 2.5, or 5.0 mg MXC (50% technical grade) via oral gavage for 5 consecutive days each week for either 2 or 4 weeks. Control groups received either 0.025 mg estradiol-17 beta (E-17 beta) or the sesame oil vehicle for the same time period. Vaginal smears were taken daily, and weights were recorded weekly. Twenty-four hours following the final exposure, animals were sacrificed. Ovaries and reproductive tracts were removed and weighed. One ovary from each animal was prepared for light microscopic evaluation. Results revealed a dose dependency of MXC in inducing persistent vaginal estrus (PVE). Ovaries of MXC-exposed and E-17 beta-exposed animals weighed significantly less than the sesame oil controls. In addition, there was an increase in the number of atretic large follicles in the E-17 beta group and in those mice treated with the two highest doses of MXC, indicating a potential reduction in the immediate fertility of the animal. Thus, this commonly employed pesticide appears to mimic closely those effects on the female reproductive system induced by estrogens.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Estradiol / pharmacology
  • Estrus / drug effects
  • Female
  • Methoxychlor / toxicity*
  • Mice
  • Ovary / drug effects*
  • Ovary / pathology*


  • Estradiol
  • Methoxychlor