Histological changes in the vulva and vagina from ovariectomised rats undergoing oestrogen treatment

The purpose of this study was to assess the histological changes occurring in the vagina and vulva in ovariectomised female rats, as well as the response to the administration of injectable oestrogens.

We used 30 female Wistar white rats, distributed as follows: group 1 - the control group, group 2 - the operated but untreated rats, and groups 3, 4 and 5 - operated rats, to which oestrogenic treatment was administered (Estradiol, Estradurin, Sintofolin) at a dosage of 0.2 mg/rat/day. After 14 days of treatment, all animals were sacrificed and vaginal and vulvar biopsies were taken from all groups.

In group 2, we encountered structural changes of the vaginal mucosa, with severe atrophy and alterations in the thickness of the vagina and vulva. In groups 3, 4 and 5 we found marked hyperplasia of the vaginal and vulvar epithelium, eosinophilic and mast cell infiltration in the chorion.

Our study proves that the histopathological changes during anoestrus after administration of oestrogens are cell hyperplasia, thickening of the superficial mucosal layer, eosinophilic and mast cells infiltrations, and chorionic congestion. Furthermore, we demonstrated that Estradiol therapy induces the most evident histological changes when compared to synthetic oestrogens such as Estradurin or Sintofolin.