RESUMEN
PIP: Samples of vaginal tissue were obtained from patients with a recorded history of exposure to nonsteroidal estrogens such as diethylstilbestrol (DES) in utero as well as from patients not exposed to DES but undergoing vaginal operations for other reasons. The tissue was removed from various sites within the vagina and divided into 2 segments, 1 fixed in 10% formalin and the other in 3.5% glutaraldehyde. The formalin series received routine histological analysis. The glutaraldehyde series was further prepared for scanning electron microscopy. As a result of exposure to DES several cervico-vaginal aberrations were noted, the most striking of which were those seen histologically. These have been classified into 5 groups: 1) complete epidermidization - complete replacement by metaplasia; 2) surface epidermidization - residual glands beneath and surface; 3) incomplete epidermidization - mixture of columnar epithelium on surface including crypts and glandlike elements; in-situ or invasive: and 5) squamous cell dysplasia. The differentiation of the early embryonic vaginal epithelium to that of the mature squamous epithelium of the newborn seems to be interfered with by the in utero exposure to nonsteroidal estrogens. It is not known whether this is due to inhibition with steroid estrogens or to some other enzymatic process. As a result of this exposure, vaginal adenosis develops. There is a natural tendency of the body to convert this adenosis to normal squamous epithelium through the process of metaplasia and the 5 states observed represent all phases of this process. In the group of patients in which the metaplastic process is incomplete or in a state of transition both columnar cells and squamous cells exist adjacent to each other and between them cells with variable degrees of metaplastic change. In a few patients these abnormal embryonic cell nests lead to the development of a malignancy, usually a mesonephromal clear-cell adenocarcinoma. Furthermore, within the areas of metaplastically converted squamous epithelium, anaplastic and dysplastic cellular changes also occur, with the potential danger of developing intraepithelial and possibly invasive squamous cell carcinomas of athe vagina.^ieng