Origin of permanently altered epithelial cells of the vagina in neonatally estrogen-treated mice.

In adult mice, neonatal injections of estrogen induce persistent, estrogen-independent cornification of the vaginal epithelium. Since the occurrence of nodules composed of affected epithelial cells (B cells) is a prodromic phenomenon of the irreversible vaginal alterations, the relationship between the occurrence of B-cell nodules and the time of DNA synthesis in the vaginal epithelial cells was examined by means of the techniques of serial mapping and autoradiography. B-cell nodules appeared in the epithelium of mullerian vagina 3-5 days after the initiation of neonatal estrogen treatment, without spatial continuity to cuboidal epithelial cells of the sinus vagina. The time of DNA synthesis was different in B cells from that in both columnar mullerian and cuboidal sinus cells, suggesting that the mother cells of B cells might be a population of still unidentified, undifferentiated cells.