title: Critical period for neonatal estrogen exposure in occurrence of mammary gland abnormalities in adult mice.
abstract: There exists a critical period for the development of cervicovaginal lesions in both mice and humans exposed neonatally and antenatally to sex hormones. Mammary glands from year-old female BALB/c mice exposed neonatally to 20 micrograms estradiol for 5 days commencing at 1 day of age showed the most mammary abnormalities, significantly greater than in controls (P less than 0.005). The incidence of abnormalities declined when treatment was begun after Day 1. Treatments begun after Day 3 did not result in this structural pattern. Mice ovariectomized after treatment all had inactive mammary glands with no abnormalities. There is a critical exposure period for the later occurrence of mammary gland abnormalities. However, the aberrant secretory state which accompanies these mammary gland alterations may be a consequence of permanent alteration in ovarian function or its endocrine control.
mesh_terms: D000375:Aging; D000818:Animals; D000831:Animals, Newborn; D004958:Estradiol / Q000633:toxicity*; D005260:Female; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000254:growth & development / Q000473:pathology*; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D004958:Estradiol