Passage of methoxychlor in milk and reproductive organs of nursing female mice; 1. Light and scanning electron microscopic observations.

To determine whether the pesticide methoxychlor can be excreted in milk, lactating mouse dams received 14 daily intraperitoneal injections of either sesame oil, or 10.0 micrograms of 17-beta estradiol, or 1.0, 2.0, or 5.0 mg of technical grade methoxychlor. At 15 days, suckling female pups were sacrificed and the effects of the chemicals in milk on the morphology of the immature reproductive tract were examined. The stimulatory changes in both the vagina and uterine horns indicate that the estradiol or methoxychlor doses were excreted in milk and remained biologically active in the suckling mice. Although the stimulatory changes from estradiol or methoxychlor were similar, the higher methoxychlor doses produced some cellular atypia in uterine horns. The possible consequences of early stimulatory influence of methoxychlor on adult reproductive organs are discussed in the text.