Cell type-specific Ca2+ signals govern mouse seminiferous tubule physiology

Spermatogenesis, the complex developmental process of male germ cell proliferation, differentiation, and maturation, is the basis of male fertility. In the seminiferous tubules of the testes, spermatozoa are constantly generated from spermatogonial stem cells through a stereotyped sequence of divisions. The basic physiological principles, however, that control seminiferous tubule function remain poorly, if at all, defined. Here, we address cell type-specific seminiferous tubule signaling in vitro and in vivo. By monitoring changes in cellular Ca2+ concentration at high spatiotemporal resolution, we show that the three cell types that build the seminiferous epithelium-Sertoli, peritubular, and germ cells-each display unique Ca2+ signaling patterns. We reveal the underlying mechanisms and demonstrate that Sertoli cell Ca2+ signals are under gonadotropin regulation. Together, our experimental findings provide insights into seminiferous tubule signaling, its mechanistic basis, and its endocrine control.