Presence of the factor that inhibits collagen synthesis and stimulates cell proliferation in developing embryonic chick skin extracts

The effects were studied of the extracts prepared from 10- and 18-day developing chick skins on collagen synthesis and proliferation of the monolayered fibroblasts established from 10-day skin. Cell proliferation was stimulated by both 10- and 18-day skin extracts at the concentration of 3.5 μg/ml. Collagen synthesis was suppressed by the treatment of extracts prepared from both 10- and 18-day skins at the concentration of 3.5 μg/ml, to a greater extent in 18-day extract. The results indicate that skin extracts possess factors exhibiting both a stimulating effect on cell proliferation and an inhibitory effect on collagen synthesis.