Functional Hierarchy and Reversibility Within the Murine Spermatogenic Stem Cell Compartment

Abstract

Sperm Production-Line Maintenance The average man makes upwards of 1500 sperm per heartbeat. Such a feat requires a robust stem cell system. Using mice, Nakagawa et al. (p. 62 , published online 18 March) shed light on some of the properties of the murine germline stem cell system that contribute to its robustness. During steady-state spermatogenesis, the majority of the stem cell population lies within a subset of cells called type A spermatogonia. However, during regeneration (for example, during recovery of the stem cell pool after drug exposure) the system in essence hijacks early-differentiating cells back into the stem cell compartment. Lineage analysis and live-imaging also suggests that during sperm production there is more than one path from a stem cell to differentiation.