Proliferation and differentiation of spermatogonial stem cells in the w/wv mutant mouse testis

Mutations in the dominant-white spotting (W; c-kit) and stem cell factor (Sl; SCF) genes, which encode the transmem-brane tyrosine kinase receptor and its ligand, respectively, affect both the proliferation and differentiation of many types of stem cells. Almost all homozygous W or Sl mutant mice are sterile because of the lack of differentiated germ cells or spermatogo-nial stem cells. To characterize spermatogenesis in c-kit/SCF mu-tants and to understand the role of c-kit signal transduction in spermatogonial stem cells, the existence, proliferation, and dif-ferentiation of spermatogonia were examined in the W/Wv mu-tant mouse testis. In the present study, some of the W/Wv mu-tant testes completely lacked spermatogonia, and many of the remaining testes contained only a few spermatogonia. Exami-nation of the proliferative activity of the W/Wv mutant sper