Structural and Ultrastructural Study, at Ovariectomised Female Rats, and their Reactivity to the Administration of Injectable Oestrogens

The purpose of this study has been to identify and emphasise structural and ultrastructural modifications occurring in the vaginal epithelium in ovariectomised female rats, as well as their reactivity to the administration of injectable oestrogens. 30 female Wistar white rats have been used, with an average weight of 200 g, distributed as follows: group 1, control group, with no treatment or intervention whatsoever, group 2, menopausal, operated group, with no treatment, and groups 3, 4 and 5, operated, to which oestrogenic treatment was administered. 15 days after surgery, the hormone replacement therapy with injectable oestrogens was initiated (Estradiol, Estradurin, Sintofolin), with a dosage of 0.2 mg/rat/day, and after 14 days of treatment, all animals were sacrificed and biopsies were taken from vaginal epithelium, after which the samples were processed in accordance with optical microscopy techniques (the semi-thin section technique) and transmission electron microscopy (TEM). In group 2, the vaginal epithelium was congested and exhibited relatively numerous invaginations of the mucosa and irregularities of the surface of the epithelium, with a decrease in the number of cells forming every layer, including the ones in the basal layer, which could no longer ensure the regeneration of all cells lost at the level of the epithelium of the superficial layer. In groups 3, 4 and 5, compared to group 2, ovariectomised, the semi-thin sections obtained revealed hyperplasia of all cellular layers of the vaginal epithelium. Ultrastructural investigations confirm the results of the structural study based on semi-thin sections, as the injectable oestrogen treatment has protected and rebuilt the structure of the vaginal epithelium, the chorion and the muscular layers affected by ovariectomy. Our study has shown that experimentally induced menopause has caused significant modifications, expressed polymorphically with alterations to various degrees of ultrastructural visualisation at the level of the entire vaginal epithelium. In all groups treated with oestrogens, it has become apparent that the vaginal epithelium is hyperplased, with the vast majority of its cells having a normal or almost normal aspect, and an isolated presence of structures that have not been completely rebuilt.