Cell Proliferation and Cell Death in Mouse Reproductive Tracts

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Apoptosis was encountered mainly in spermatids and spermatocytes in surgically induced bilateral cryptochidism of male mice. Expression of TNF-alpha receptor, TGFbeta2, beta3 and Fas mRNAs increased in the cryptorchid testes within 24 h after the operation. In order to study the mechanism of mammary gland involution, litters were removed on day 20 of lactation and morphological and biochemical changes were examined in GR/A mice and lpr^<cg> mice lacking functional Fas. Apoptotic cell death occurs during involution of mammary gland with the increase of mRNA expression of TNF-alpha and TGF-beta1. TNF-alpha and anti-Fas antibody directly killed more than 80% of mammary cells from p53 knockout mice in vitro within 24 h in the presence of actinomycin D,supporting the hypothesis that Fas and/or TNF-alpha are involved in the induction of apoptosis of mouse mammary glands. Pregnancy-dependent mammary tumors (PDMT) and transplantable PDMT (TPDMT-4), are exceptionally stable in hormone dependence, continue to grow until parturition and regress soon after deliverly. Apoptosis occurs in the regressing PDMT and TPDMT-4 on day 20 or 18 of pregnancy, and on the parturient and the following days, respectively.Perinatal treatment of female mice with diethylstilbestrol (DES) results in estrogen-independent persistent proliferation and cornification of vaginal epithelium. Expression of c-jun and c-fos mRNAs was greater in the vagina of neonatally DES-exposed mice than in controls. Neonatal exposure to DES and tamoxifen induced permanent changes in the pelvis and femur. Rodent uterus and vagina show marked histological changes during the estrous cycle. There is an inverse correlation between cell death and cell proliferation in rat uterine and vaginal epithelial cells during the estrous cycle.