Effects of estrogen treatment on persistent hyperplastic lesions of the vagina in neonatally estrogenized mice.

Abstract

Female mice of B6AF1 hybrids (C57BL/6N .times. A/HeN) were treated neonatally with 5 daily injections of 20 .mu.g estradiol-17.beta. or sesame oil from the day of birth. About half were ovariectomized at 40 days of age, and the others had an estradiol-17.beta. pellet implanted under the dorsal skin at 80 days of age. The pellet was removed 30 days later. Vaginal smear records showed persistent vaginal cornification in a number of neonatally estrogenized mice regardless of ovariectomy. When killed at 16-21 mo. or at 24-32 mo. of age, hyperplastic lesions ranging histologically from those resembling squamous cell carcinomas to adenosis-like structures were observed in neonatally estrogenized mice. The development of lesions was more pronounced in mice killed at 24-32 mo. of age than at 16-21 mo. Secondary estrogen treatment in adults did not appreciably affect the promotion of lesions. Neonatal exposure to high doses of estrogen was important, primarily in connection with the neoplastic changes in the cervicovaginal tract.