Fine structure of juvenile feathers of the zebrafinch in relation to the evolution and diversification of pennaceous feathers.

The present ultrastructural study describes the formation of feather ramification in developing juvenile feathers of the zebrafinch, a small passeraceous bird. The study stresses the importance of the detailed knowledge on the cell structure of barb ridges for the understanding of feather development and evolution. Feather formation depends on the morphogenesis of long barb ridges, in which cells are displaced into lateral barbule plates and a...