Embryonic feather bud development - a keystone model for vertebrate organogenesis

The development of feathers in the embryonic skin has been used as a model for biological self-organisation for many decades. The availability, size and ease of manipulation of the skin has enabled it to serve as a model revealing concepts of epithelial-mesenchymal interaction, origins of periodic patterns in the anatomy, and the effects of growth factors and structural and mechanical properties on tissue development. These efforts provide a rich history of observation, informing continued development of new concepts in this system. Here we review the process of early feather bud development, the understanding gained from decades of experimentation, and current debate and future directions for progress.