Stratified squamous metaplasia of the uterine epithelium in early androgen‐treated rats and its inhibition by light deprivation

Rats, having been given a single subcutaneous injection of testosterone propionate at four days of age, exhibited polyfollicular ovaries, extensive stratified squamous uterine metaplasia and persistent vaginal cornification (90–95% of the smears contained cornified cells) after adulthood was attained. If early androgentreated rats were blinded at 22 days of age the number of vesicular follicles in the ovaries of adults was greatly diminished, the incidence and extent of stratified squamous metaplastic lesions were suppressed and the number of vaginal smears containing cornified cells was reduced by about 50%. The effects of blinding, however, were negated by pinealectomy illustrating that the suppressive influence of light deprivation on reproduction was mediated by way of the pineal gland.