The human VASA gene is specifically expressed in the germ cell lineage

To understand the origins and function of the human germ cell lineage and t o identify germ cell-specific markers we have isolated a human ortholog of the Drosophila gene vase, The gene was mapped to human chromosome 5q (near the centromere) by radiation hybrid mapping. We show by Northern analysis o f fetal and adult tissues that expression of the human VASA gene is restric ted to the ovary and testis and is undetectable in somatic tissues. We gene rated polyclonal antibodies that bind to the VASA protein in formalin-fixed , paraffin-embedded tissue and characterized VASA protein expression in hum an germ cells at various stages of development. The VASA protein is cytopla smic and expressed in migratory primordial germ cells in the region of the gonadal ridge. VASA protein is present in fetal and adult gonadal germ cell s in both males and females and is most abundant in spermatocytes and matur e oocytes, The gene we have isolated is thus a highly specific marker of ge rm cells and should be useful for studies of human germ cell determination and function.