Germ cell sex determination - Piecing together a complex puzzle

In many multicellular organisms, proper germ cell development is crucial for production of future generations. One critical step in this process is the decision of germ cells to develop into either sperm or eggs. Defects in germ cell sex determination can lead to infertility and germ cell tumors. However, while much is known about somatic sex determination, regulation of germ cell sex is not well understood. Recent studies with Drosophila reveal that the janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway promotes male germ cell development during early stages of gonad morphogenesis. 1 Here, this and other work suggesting that the JAK/STAT pathway acts alongside a host of other factors to regulate germ cell sex determination is discussed. Furthermore, recent insights into mouse germ cell sex determination are reviewed; revealing a number of correlations that suggest similar mechanisms may regulate aspects of both mouse and Drosophila germline sexual dimorphism.