Figure 3.

(A–D) Representative high-magnification ERα immunostaining within the uterine tissue of rat offspring after in utero treatment with EE2 and 0.1 and 50 mg BPA compared with the negative controls. ERα immunoreaction was recognized in nuclei of both epithelium (arrowheads) and stromal cells (arrows). (A) Control (cornstarch-treated animals) group. Weak ERα immunoreaction in nuclei of both epithelium and stromal cells. Less ERα-immunostained luminal epithelium cell nuclei. Original magnification, x400. (B) 0.2 mg/kg per day EE2 (positive control). Significantly increased population of ERα-immunostained uterine luminal epithelial cell nuclei, as well as a strongly immunostained stromal cell pattern frequently describing a uniform, thick mesenchymal cell layer underlying the luminal epithelium. Original magnification, x400. (C) 0.1 mg/kg per day BPA. Weak ERα immunoreaction in nuclei of both epithelium and stromal cells. Less ERα-immunostained luminal epithelium cell nuclei. Original magnification, x400. (D) 50 mg/kg per day BPA. Significantly increased population of ERα-immunostained uterine luminal epithelial cell nuclei, as well as strongly immunostained stromal cells, which are not organized in a uniform cell layer underlying the epithelium. Stronger immunostaining was also recognized in the cytoplasm of luminal epithelial cells. Original magnification, x400. (E) Image analysis score of positive ERα-immunostained uterine luminal epithelial cells. Shown is the percentage of ERα-immunostained uterine epithelial cell nuclei. Values are based on analysis of nine fields from each section (two sections per uterus) in six rats from each group and are reported as the mean ± SD. Co, control (cornstarch-treated animals) group, 57 ± 19%, n = 6; EE2, 0.2 mg/kg per day 17α-ethinyl estradiol group, 90 ± 4%, n = 6; BPA0.1, 0.1 mg /kg / day BPA, 67 ± 7%, n = 6; BPA50, 50 mg/kg per day BPA, 95 ± 15%, n = 6.