Spermatogonial stem cells (SSCs) can self-renew and maintain their undifferentiated state. A continuous supply of differentiating germ cells is essential for spermatogenesis. SSCs constitute a small fraction of the adult testicular germ cells. Approximately 30,000 SSCs exist in each adult mouse testis and are located in the most peripheral region of the seminiferous tubule. SSCs either undergo self-renewal divisions, that generate new SSCs to ensure maintenance of the stem cell pool, or divide into differentiating spermatogonia.
Two classes of spermatogonium have been identified by functional criteria:
Spermatogonial stem cells that can colonize a recipeint testis after germ cell trasplantation and differentiated spermatogonia that are incapable of colonizing the testis and are further categorized as either type A or B, depending on their appearance and pattern of gene expression.
Multiple AncestorsSingle AncestorNo DescendantsDevelops fromPart of Parent