Formation of normal plumage
Researchers disrupted the Shh signaling pathway in chicken embryos nine days into development, which is when feathers begin to form.
This led to the development of simple, proto-feather-like buds.
Surprisingly, the embryos partially recovered after the 14th day despite initially disrupting feather development by blocking the Shh pathway. Even though chicks hatched with bald patches, their bodies reactivated dormant follicles, resulting in the development of normal plumage.
Researchers used light sheet fluorescence microscopy, a laser-based imaging technique, to observe feather development in chicken embryos.