[Fundamental studies on high risk factor of endometrial carcinoma functional and histological abnormalities of ovaries and uteri in experimental anovulatory rats (author's transl)]

Abstract

Anovulatory sterility is considered as one of high-risk factors of endometrial adenocarcinoma. We produced an animal model of anovulation in Sprague-Dawley rats and compared the changes of reproductive organs, such as ovary and uterus, of androgen sterilized rats (ASR) with normal rats (NR). The results obtained were as follow: 1) Vaginal opening was observed at 45 days of age in all of NR, however it was observed in 63% of ASR at 300 days of age. 2) Infertility rate of ASR was 98%, and all of ASR revealed persistent estrus. 3) The ovarian and uterine weights of ASR were smaller than those of NR. 4) Numerous vesicular follicles and absence of corpora lutes were characteristics in the ovary of ASR. 5) Severe hyperplasia of the endometrium was recognized in 5 of 49 ASR, including 2 atypical hyperplasia. 6) Serum progesterone levels of ASR was significantly lower than that of NR. Therefore E/P ratio increased in ASR. 7) The uterine sensitivity of ASR to gonadectomy and estradiol administration was reduced. These results indicate that uterus of ASR is tonically stimulated by estrogen and that androgenization also causes proliferative alterations in uterine morphology.