Histopathology of uteri (A to D) and vaginae (E to F) of rats infected with C. trachomatis following intrauterine treatment with saline (A and E), estradiol (B and F), progesterone (C and G), or estradiol and progesterone (D and H). Animals were sacrificed 5 days postinfection; reproductive tract tissues were removed, fixed, processed for histology, and stained with hematoxylin and eosin. Representative tissue sections from each treatment groups are shown. Estrogenic effects on epithelial cells of uteri and vaginae of rats receiving estradiol can be observed (B, D, F, and H). Note the acute inflammation in the uterus of a progesterone-treated rat, characterized by large number of infiltrating leukocytes (C). s, stroma; l, lumen; e, epithelium. Original magnification, ×100.