Transcriptional regulator that plays a key role in germ cell development (PubMed:16982049, PubMed:21123517, PubMed:32054698). Determines the oogenic fate by activating key genes for the oogenic program and meiotic prophase entry (PubMed:32054698). Acts downstream of bone morphogenetic protein (BMP) by regulating expression of genes required for the oogenic programs, which are repressed by Polycomb activities in sexually uncommitted germ cells (PubMed:32054698). Regulates expression of STRA8, a central downstream effector for the meiotic program (PubMed:32054698). Acts independently of retinoic acid (RA) (PubMed:32054698). In males, not required for germ-cell sex determination, but required to allow the spermatogonia to efficiently accomplish the meiotic prophase (PubMed:32054698). Specifically expressed in adult testis and ovary (PubMed:16982049). Expressed at high levels in the somatic cells of the developing gonads, including Leydig cells in the testes and granulosa cells in the ovaries (PubMed:16982049). During female embryogenesis, specifically and transiently expressed in germ cells expressing Ddx4: expression starts at 12.0 dpc and decreases after 14.5 dpc, a key period for the sex determination of germ cells (PubMed:21123517, PubMed:32054698). Not expressed in somatic cells or males during embryogenesis (PubMed:32054698). Up-regulated in response to bone morphogenetic proteins (BMPs) signaling. Mice are viable and normal; however, both males and females are completely infertile (PubMed:16982049, PubMed:32054698). In females, Zglp1 absence leads to a severe block in germ cell development as early as 17.5 dpc (PubMed:16982049). Ovaries at postnatal day (P) 8 and 6 weeks are highly atrophic with no ovarian follicles (PubMed:32054698). Ovaries as early as 17.5 dpc contain a drastically reduced number of cells expressing Ddx4 (PubMed:32054698). In males, Zglp1 absence leads to defective sperm development with a marked reduction in mature spermatids observed as early as postnatal week 1 (PubMed:16982049). Male germ cells develop normally until P7 (PubMed:32054698). Subsequently, they display severe impairment in the first wave of spermatogenesis: unlike in females, germ cells entered into meiotic prophase, but fail to progress beyond the zygotene stage, resulting in a large fraction of abnormal pachytene cells both at P15 and P20 (PubMed:32054698).