Differentiation in vitro: effects of Sephadex fractions of chick embryo extract.

Chicken embryo extract has been fractionated into high-and low-molecular-weight components on Sephadex G-25. Media supplemented with the low-molecular-weight fraction (L) support full differentiation in clones of cartilage and of pigmented retina cells from chicken embryos. Growth rates of such cultures in L-supplemented media are greater than in media without embryo extract, and plating efficiencies are higher than in media with or without whole embryo extract. The high-molecular-weight fraction (H) in low concentrations also stimulates growth and plating efficiency, but inhibits the expression of differentiation.