Synthesis of two collagen types by embryonic chick corneal epithelium in vitro

To better understand the mechanisms involved in matrix development, we have analyzed the collagen synthesized by embryonic corneal epithelium, the tissue known to produce the collagenous component of the primary corneal stroma. Isolated epithelia were cultured in vitro in medium containing [oH]proline and the newly synthesized, labeled collagen was extracted, fractionally salt precipitated, and analyzed by carboxymethyl-cellulose chromatography and peptide mapping after cleavage with cyanogen bromide. The data show that the cornela epithelium produces at least two different types of collagen, one similar, if not identical, to the type I molecule of skin, and a second similar, if not identical, to the type II molecule of cartilage. Type II, heretofore, had been thought to be characteristic of cartilage extracellular matrix.