[Experimental studies on spontaneous occurrence of uterine adenocarcinoma (author's transl)]

Abnormal uterine proliferation was not detected in all 111 control normal rats (NR) during 750 days' observation period. In androgen sterile rats (ASR), 4 squamous metaplasias were detected in 25 ASR at 70-100 days of age. Thereafter, 9 squamous metaplasias and 2 non-atypical hyperplasias were detected in 20 ASR at 200-360 days of age. At 500-750 days of age, 12 squamous metaplasias, one non-atypical hyperplasia, 2 atypical hyperplasias and 2 adenocarcinomas were detected. Histological examination revealed that one of adenocarcinoma was composed of well differentiated type, poorly differentiated type and squamous metaplasia. Another case was composed of poorly differentiated adenocarcinoma, squamous cell carcinoma and squamous metaplasia. Hormonal environment of ASR with adenocarcinoma was characterized by an increase in estrogen/progesterone ratio, as compared to NR. After 500 days of age, 2 pituitary, 6 mammary and 3 adrenal tumors were detected in 33 NR, whereas 2 pituitary and 2 mammary tumors were detected in 25 ASR.