Ultrastructure of vagina and uterus in young mice after methoxychlor exposure.

Ultrastructural effects of 17 beta-estradiol were compared with technical pesticide methoxychlor in uterus and vagina of young mice. Neonates received 14 daily ip injections of either sesame oil, 10.0 micrograms 17 beta-estradiol, or 0.05, 0.1, 0.5, or 1.0 mg methoxychlor. Estradiol accelerated vaginal opening to 11 days, increased reproductive tract weight gain, and induced vaginal cornification, the cells of which exhibited complex surface microridge patterns. The hypertrophied uterine cells were covered with dense, enlarged microvilli with bulbous expansions or clumps. The highest three methoxychlor doses were stimulatory. Exposure to 0.5 or 1.0 mg methoxychlor increased reproductive tract weights threefold due to excessive fluid accumulation, and induced vaginal cornification and opening by 10 days. The cornified cells lacked complex surface microridges, while uterine cells exhibited dense microvilli growth, atypical morphology, and separation. Although 0.5 and 1.0 mg methoxychlor were highly stimulatory, the surface alterations in uterus and vagina appeared different from estradiol.