c-Flip(L) is expressed in undifferentiated mouse male germ cells.

Apoptosis represents a fundamental process during fetal/post-natal testis development. Therefore pro- and antiapoptotic proteins are essential to regulate testis physiology. c-FlipL is a known inhibitor of caspase 8/10 activity; in this study its perinatal expression in mouse male germ cells was investigated. In testis sections and seminiferous tubule whole mount c-FlipL was found to be expressed in undifferentiated spermatogonia and to co-localize with germ stem cells markers. In vivo investigations in the vitamin-A deficient mouse, lacking differentiated germ cells, confirmed c-FlipL expression in undifferentiated spermatogonia. Further analyses showed Fas expression but no significant caspase 8/10 activity when c-FlipL was highly expressed. Altogether these data suggest that c-Flip may control the survival rate of undifferentiated spermatogonia