Figures
In vivo sonic hedgehog pathway antagonism temporarily results in ancestral proto-feather-like structures in the chicken
The morphological intricacies of avian feathers make them an ideal model for investigating embryonic patterning and morphogenesis. In particular, the sonic hedgehog (Shh) pathway is an important mediator of feather outgrowth and branching. However, functional in vivo evidence regarding its role during feather development remains limited. Cooper and Milinkovitch demonstrate that an intravenous injection of sonidegib, a potent Shh pathway inhibitor, at embryonic day 9 (E9) temporarily produces striped domains (instead of spots) of Shh expression in the skin, arrests morphogenesis, and results in unbranched and non-invaginated feather buds—akin to proto-feathers—in embryos until E14. Overall, they provide functional evidence for the role of the Shh pathway in mediating feather morphogenesis and confirm its role in the evolutionary emergence and diversification of feathers. The image shows the wing of a chick embryo at the twelfth day of incubation, with feather buds covering the entire embryonic wing.
Image Credit: Rory Cooper Michel Milinkovitch
Citation: (2025) PLoS Biology Issue Image | Vol. 23(3) April 2025. PLoS Biol 23(3): ev23.i03. https://doi.org/10.1371/image.pbio.v23.i03
Published: April 10, 2025
Copyright: © 2025 . This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
The morphological intricacies of avian feathers make them an ideal model for investigating embryonic patterning and morphogenesis. In particular, the sonic hedgehog (Shh) pathway is an important mediator of feather outgrowth and branching. However, functional in vivo evidence regarding its role during feather development remains limited. Cooper and Milinkovitch demonstrate that an intravenous injection of sonidegib, a potent Shh pathway inhibitor, at embryonic day 9 (E9) temporarily produces striped domains (instead of spots) of Shh expression in the skin, arrests morphogenesis, and results in unbranched and non-invaginated feather buds—akin to proto-feathers—in embryos until E14. Overall, they provide functional evidence for the role of the Shh pathway in mediating feather morphogenesis and confirm its role in the evolutionary emergence and diversification of feathers. The image shows the wing of a chick embryo at the twelfth day of incubation, with feather buds covering the entire embryonic wing.
Image Credit: Rory Cooper Michel Milinkovitch