Inhibition of Morphogenesis and Stimulation of Vascular Proliferation in Embryonic Tooth Cultures by a Sarcoma Growth Factor Preparation1

Sarcoma growth factor (SGF) induces proliferation and an chorage-independent growth of nonmalignant cells. It competes with epidermal growth factor (EGF) for the EGF-receptors at the cell surface. SGF-like factors have recently been isolated from embryos, suggesting that SGFs may represent embryonic forms of EGF. Therefore, we have tested whether SGF preparations affect organogénesis and differentiation of cultured embryonic tissues. The embryonic tooth rudiments were cultivated in the presence of SGF and EGF. Stimulation of vascularization was seen in both of these organ cultures. Therefore, we propose that endothelial cells may be target cells for SGF, and SGF may be involved in the control of vascularization during embryogenesis. SGF and also, to a certain extent, EGF profoundly inhibited morphogenesis and differentiation of the tooth germ, with con comitant stimulation of vascularization. Analysis of cell prolifera tion revealed that some cell types of the tooth germ did not respond to SGF by proliferation, while a stimulation by EGF was observed. Nevertheless, tooth morphogenesis was also slightly inhibited by EGF, suggesting that growth factors which enhance proliferation do not necessarily stimulate morphogenesis and differentiation. Since the SGF preparations contain several fac tors, the effects observed could be due to the action of one or more factors.