Evidence for a role of basic fibroblast growth factor in rat embryonic growth and differentiation

The possibility that basic fibroblast growth factor (FGF) plays a role in the regulation of mammalian embryogenesis was investigated. When transplanted under the renal capsule of syngeneic juvenile hosts, 10-day-old rat embryos grow rapidly, and tissue differentiation occurs in an essentially normal manner. Infusion of antiserum to bovine FGF into the renal artery of kidneys bearing such transplants significantly retarded their growth, and differentiation of all tissues of endodermal and some of those of mesodermal origin was completely suppressed; differentiation of other tissues of mesodermal origin was partially inhibited. Infusion of nonimmune serum had no such effects. Infusion of recombinant bovine FGF into the renal artery stimulated growth of embryo transplants on the infused kidney, but not of those under the renal capsule of the contralateral kidney, and it did not affect growth of the infused kidney itself. These results suggest that FGF may be important for growth and differentiation of endodermal and some mesodermal tissues of mammalian embryos.