The mouse homolog of Drosophila Vasa is required for the development of male germ cells

Restricted expression of a mouse Vasa homolog gene (Mvh) expression is firs t detected in primordial germ cells (PGCs) after colonization of the genita l ridges. Subsequently, Mvh is maintained until postmeiotic germ cells are formed. Here, we demonstrate that male mice homozygous for a targeted mutat ion of Mvh exhibit a reproductive deficiency. Male homozygotes produce no s perm in the testes, where premeiotic germ cells cease differentiation by th e zygotene stage and undergo apoptotic death. In addition, the proliferatio n of PGCs that colonize homozygous male gonads is significantly hampered, a nd OCT-3/4 expression appears to be reduced. These results indicate that th e loss of Mvh function causes a deficiency in the proliferation and differe ntiation of mouse male germ cells.