Skin field formation: morphogenetic events.

Abstract

This chapter is mostly a review of the pioneering work of the Philippe Sengel school in Grenoble carried out in the late sixties and the seventies. The questions raised concerning the morphogenesis of feather tracts were approached by means of microsurgery on chick embryos. P. Sengel and his wife M. Kieny had the feeling that proteins synthesized by the neural tube were required for the formation of feather fields. It was my pleasure to carry on the story from the beginning. Although some clarifications concerning this morphogenesis have been contributed by my group and by a few other laboratories interested in this subject, the most important contributions to recent research have been the elucidation of the nature of the required messages, which will be explored further in other papers in this Issue.

Scale development in fish: a review, with description of sonic hedgehog (shh) expression in the zebrafish (Danio rerio).

“…5B) is characterised by the segregation of fibroblasts in particular regions, corresponding to the chessboard pattern on the skin (see above). These two steps are similar to what happens during skin formation in amniotes (Dhouailly, 2004). These subsets of fibroblasts continue their differentiation process and proliferate, as indicated by the numerous mitotic pictures, to form scale papillae.…”

The different steps of skin formation in vertebrates.

“…2B) . Thus, in scaleless embryos Dhouailly et al, 1998; (Wessells, 1965; see also review by Dhouailly et al, 2004), the formation of a dermis in areas which correspond to the pterylae is characterized by an increase in the cellular density of the fibroblasts. In scaleless embryos, however, the next step does not occur.…”

Ventral vs. dorsal chick dermal progenitor specification.

“…The best results were obtained with the neural tube and the agar implant. In half of those cases the surviving embryos exhibited an ectopic pteryla in the midventral apterium (reviewed by Dhouailly et al, 2004). These ectopic pterylae were circular and separated from the normal feather tracts by a semi-apterium.…”