[Pathological study of endometrial carcinogenesis in androgen-sterilized-rats]

As reported previously, squamous metaplasias, endometrial hyperplasias and cancers of the uterus occurred more frequently in androgen-sterilized-rats (ASR) than in normal rats (NR). This time we pathologically examined the endometrium of ASP in detail and obtained the following results: 1) In NR, aged from 70 to 750 days, no abnormal findings were found. In 61 ASR, aged more than 500 days, were found 8 simple endometrial hyperplasias, 2 atypical endometrial hyperplasias, 15 simple squamous metaplasias, 1 atypical squamous metaplasia, 2 adenocarcinomas, 1 adenosquamous carcinoma and 1 squamous carcinoma. 2) In ASR, proliferative and metaplastic changes coexisted in the endometrium. Two adenocarcinomas were accompanied by metaplasias and atypical hyperplasias, and one squamous carcinoma was accompanied by simple hyperplasias. 3) The endometrial carcinogenesis of ASR was thought to be as follows. In ASR, the endometrial epithelium loses its secretory function, becoming low columnar epithelium. A part of the non-secretory endometrium gains proliferative activity and progresses to metaplastic epithelium or to glandular hyperplasia. The former may develop to atypical metaplasia and squamous carcinoma, the latter to atypical hyperplasia and adenocarcinoma.