Somatic Cyst Cells as a Microenvironment for the Maintenance and Differentiation of Germline Cells in Drosophila Spermatogenesis

The functions of somatic cells in multicellular organisms are essential for the maintenance of germline stem cells and the formation of gametes and, ultimately, for the survival of species. In Drosophila testes, two populations of somatic cells function as microenvironments of germ cells. A group of terminally differentiated cells at the apical end of the testis, hub, directly contacts with germline stem cells, regulating their self-renewal and proliferation by secreting signaling molecules. Another population of testis somatic cells, somatic cyst cells, plays an important role both in the maintenance of germline stem cells and in the processes of directed differentiation of their daughters, modulating external signals and creating a microenvironment of differentiating germ cells throughout spermatogenesis. The review is devoted to the analysis of modern data on the molecular and cellular mechanisms and protein complexes required in somatic cyst cells for nonautonomous regulation of germ line cell development.