The ratio of soluble to insoluble collagen in normal chick dermis.

Weiss and Matoltsy (1) reported a total absence of wound healing in chick embryos prior to the tenth day of incubation. The epithelial cells of the wound margin, instead of covering the wound surface as they do in older embryos, penetrate the underlying mesenchymal stroma. We thought that the explanation for this behavior of the epithelium should be sought in the embryonic mesenchyme.The importance of the mesenchyme, e.g., the dermis, for the differentiation of the epidermis and its derivatives during embryogenesis has been well established (2-5). Differentiation and proliferation of epidermal cells in newts was found to be dependent on mesenchymal factors (6). McLoughlin (7) was able to alter specifically the differentiation of embryonic epidermis by combination with mesenchyme from various organs. Epidermal cells cultured without mesenchyme do not differentiate but degenerate, whereas frozen-thawed mesenchyme is able to support epidermal differentiation (8).This property of frozen-thawed mesenchyme, how...