The role of stem cell factor and of alternative c-kit gene products in theestablishment, maintenance and function of germ cells

The c-kit gene plays a fundamental role during the establishment, the maint enance and the function of germ cells. In the embryonal gonad the c-kit tyr osine kinase receptor and its ligand Stem Cell Factor (SCF) are required fo r the survival and proliferation of primordial germ cells. In the postnatal animal, c-kit/SCF are required for the production of the mature gametes in response to gonadotropic hormones, i.e. for the survival and/or proliferat ion of the only proliferating germ cells of the testis, the spermatogonia, and for the growth and maturation of the oocytes, Finally, a truncated c-ki f product, tr-kit, specifically expressed in post-meiotic stages of spermat ogenesis and present in mature spermatozoa, causes parthenogenetic activati on when microinjected into mouse eggs, suggesting that it might play a role in the final function of the gametes, fertilization.