Representative histological features of cervical epithelium from untreated and estrogen-treated K14-E7 transgenic mice compared with nontransgenic mice. We evaluated the epithelial histopathology in a total of 40 mouse cervical tissues. Ten samples each from untreated nontransgenic (Nt-E), 17β-estradiol treated (6 months) nontransgenic (Nt+E), untreated K14-E7 transgenic (E7-E) and estrogen-treated K14-E7 transgenic (E7+E) mice were included in this study. Control Nt-E mice show thin cervical epithelium (A). In contrast, Nt+E mice exhibit wider cervical epithelium (B). Thick cervical epithelium constituted by cells with slight dysplasic changes are apparent in E7-E mice (C). In comparison, cervical epithelium from E7+E mice show lack of differentiation with evident dysplastic changes (D) (indicated by black arrows). (All micrographs at 400× magnification, H-E stained cross sections).