Open niche regulation of mouse spermatogenic stem cells

This review has summarized the recent findings about the nature and regulation of spermatogenic stem cells in the seminiferous tubules of the mouse testis. The niche microenvironment looks quite different with that of authentic “definitive” stem cell niche, representing the “open” niche. In mammalian testes, robust stem cell functions ensure the continual production of sperm. In testicular seminiferous tubules, spermatogenic stem cells (SSCs) are highly motile and are interspersed between their differentiating progeny, while undergoing self ‐renewal and differentiation. In such an “open niche” microenvironment, some SSCs proliferate, while others exit the stem cell compartment through differentiation; therefore, self‐renewal and differentiation are perfectly balanced at the population (or tissue) level, a dynamics termed “pop ulation asymmetry.” This is in stark contrast to the classical perception of tissue stem cells being cells that are clustered in a specialized “closed niche” region and that invariantly undergo asymmetric divisions. However, despite its importance, how the self‐renewal and differentiation of SSCs are balanced in an open niche environment is poorly understood. Recent studies have thrown light on the key mechanism that enables SSCs to follow heterogeneous fates, although they are equally exposed to signaling molecules controlling self‐renewal and differentiation. In particular, SSCs sh ow heterogeneous susceptibilities to differ...
Source: Development, Growth and Differentiation - Category: Research Authors: Tags: REVIEW ARTICLE Source Type: research