Morphological action of tamoxifen in the endometrium of persistent estrous rats

Background. The aim of this study was to evaluate the action of tamoxifen on the endometrium in states of chronic anovulation. Methods. Thirty-eight rats inducted to persistent estrous (testosterone propionate) confirmed by hormonal colpocytology were divided into a control and an experimental group; the latter received tamoxifen and had fragments of the uterine horns processed for morphological and morphometrical analysis. Data were analysed statistically by the Mann-Whitney and Student's t tests. Results. Our findings revealed minor uterine weight, epithelial thickness; number of endometrial glands and low eosinophil counts in the group that received tamoxifen. These results were statistically significant. We often observed areas of metaplasic stratified squamous epithelium between cylindrical epithelial cells in both groups. Conclusions. Our results indicate that antiestrogenic effect of tamoxifen was only partial in persistent estrous, since there was no blocking against the squamous metaplasia of the endometrium.