The Caenorhabditis elegans gonad: a test tube for cell and developmental biology.

Sexual reproduction of multicellular organisms depends critically on the coordinate development of the germ line and somatic gonad, a process known as gonadogenesis. Together these tissues ensure the formation of functional gametes and, in the female of many species, create a context for production and further development of the zygote. Since the future of the species hangs in the balance, it is not surprising that gonadogenesis is a complex process involving conserved and multi-faceted developmental mechanisms. Genetic, anatomical, cell biological, and molecular experiments have established the nematode Caenorhabditis elegans as a paradigm for studying gonadogenesis. Furthermore, these studies demonstrate the utility of C. elegans gonadogenesis for exploring broad issues in cell and developmental biology, such as cell fate specification, morphogenesis, cell signaling, cell cycle control, and programmed cell death. The synergy of molecular genetics and cell biology conducted at single-cell resolution in real time permits an extraordinary depth of analysis in this organism. In this review, we first describe the embryonic and post-embryonic development and morphology of the C. elegans gonad. Next we recount seminal experiments that established the field, highlight recent results that provide insight into conserved developmental mechanisms, and present future prospects for the field.