Experimental Conditions in which Feather Morphogenesis predominates over Scale Morphogenesis in Bird Embryos

Abstract

THE embryonic skin of birds is the site of morphogenetic interactions between the epidermis and dermis leading to the formation of cutaneous appendages1–3. Recombinations of the dermis and epidermis from the dorsal feather-forming region and the tarsometatarsal scale-forming area show that the dermis plays a decisive part in the regional differentiation of the skin1,2. The development of epidermal structures such as feathers and scales is generally determined by the regional origin of the associated dermis. In specific heterochronous combinations, however, the epidermis tends to impose the nature of its differentiation according to its own regional quality. An example of this occurs when the dorsal feather-forming 6–7 day old epidermis is associated with tarsometatarsal scale-forming 11–12 day old dermis. In such combinations a conflicting situation appears to be created which leads to the formation of either feathers and scales or feathers alone. Because the production of scales alone is not observed in these conditions, it seems that feather morphogenesis predominates over scale morphogenesis.