  Spermatogenesis is sustained by the proliferation and differentiation of
spermatogonial stem cells (SSCs). SSCs are derived from primordial germ cells
(PGCs) during embryonic development. The signal from the mammalian embryonic
tissue is critical to the localization of PGCs and various factors and
signaling pathways are involved into the regulation of these process. However,
the molecules controlling these processes still need further clarification. In
this concise review, the origin, development, differentiation of SSCs and
regulating mechanisms throughout these processes are summarized and discussed
in details. Finally, we mainly focused on elaborating the functions of
TGF-\b{eta} superfamily proteins and BMP4 in regulating SSCs formation and
differentiation.
