Apoptosis of fetal testicular cells is regulated by both p53-dependent andindependent mechanisms

A portion of fetal germ cells undergoes apoptosis in the physiological cont ext, but the molecular mechanisms of their apoptosis are largely unknown. B ecause p53 tumor suppressor gene product promotes apoptosis in various type s of cells, we have investigated the expression of p53 in fetal gonads and examined the influence of loss of p53 function in fetal gonad cells using m ice deficient in the p53 gene. We found that the expression of p53 protein in fetal testis was induced after 15.5 dpc (days post coitum), while the ex pression was not detected in fetal ovary. The number of apoptotic cells fou nd in the seminiferous tubules of fetal testes was not significantly differ ent between p53-deficient and wild-type mice until 16.5 dpc. At 17.5 dpc, h owever, more apoptotic cells were observed in wild-type testes than in the p53-deficient mice. In contrast, a similar number of apoptotic cells was fo und in fetal ovaries throughout these developmental stages. These observati ons indicate that p53 pro motes apoptosis of fetal testicular cells after 1 6.5 dpc. Mol. Reprod. Dev. 55:399-405, 2000. (C) 2000 Wiley-Liss, Inc.