Growth factor regulation of mouse primordial germ cell development.

This chapter focused on three key regulators of PGC survival and proliferation; SLF, LIF, and bFGF. The survival of all animal cells may require multiple polypeptide factors and PGCs seem to be no exception (Fig. 7). A number of lines of evidence suggest that membrane-bound forms of SLF may be required for PGC survival. These data suggest an exquisite mechanism for controlling both PGC survival and migration. Thus PGCs that stray from the normal migratory pathway might be eliminated through programmed cell death. SLF, together with LIF, can stimulate PGC proliferation in culture and it seems likely that LIF or a related cytokine may function in vivo to regulate PGC survival and proliferation. Animals doubly deficient in LIF and its relatives may soon allow the roles of these cytokines in PGC development to be determined. Although bFGF is a potent PGC mitogen in vitro, whether PGCs ever encounter bFGF in vivo remains questionable since in culture it alters both the proliferative and developmental potential of PGCs. TGF beta or MIS may be important negative regulators of PGC development, and mice lacking these factors should allow their role in PGC development to be assessed.