Practice question

Spermatogonial stem cells reside along basement membrane of seminiferous tubules within specialized niche maintained by Sertoli cells producing glial-derived neurotrophic factor GDNF and fibroblast growth factor FGF2. In steady-state spermatogenesis they undergo self-renewing divisions to maintain pool and simultaneously produce differentiating spermatogonia that ultimately yield haploid spermatozoa through meiosis. Although capable of long-term self-renewal like other adult stem cells, lineage tracing demonstrates in vivo they generate only sperm lineage, and during prolonged culture can regain pluripotency if reprogrammed. Under physiological conditions they are classified as unipotent committed to male gamete lineage.