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Dorsal dermis of the scaleless (sc/sc) embryo directs normal feather pattern formation until day 8 of development

We have examined the ability of the scaleless (sc/sc) backskin dermis (6 to 16 days of incubation) to regulate pattern formation using the presumptive scutate scale epidermis from 11‐day normal embryos as the responding tissue. Prior to 8 days of incubation the sc/sc backskin dermis is able to induce hexagonally patterned and uniformly oriented feather germs in normal epidermis. This ability is lost during day 8 and follows a central to lateral gradient. Such gradients are characteristic of normal feather development in the spinal tract. We discuss the change in the inductive ability of the sc/sc dermis in relation to the stabilization of the feather pattern, which occurs all at once throughout the dorsal dermis at 7.5–8 days of development. After day 8 until day 10, the sc/sc backskin dermis only supports the formation of sporadic, unpatterned feather germs; thereafter it will not support feather formation. © 1996 Wiley‐Liss, Inc.