CHICK DELTA-1 GENE-EXPRESSION AND THE FORMATION OF THE FEATHER PRIMORDIA

The chick dermis is known to control the formation of feathers and int erfeathery skin in a hexagonal pattern. The evidence that the segregat ion of two types of fibroblasts involves Delta/Notch signalling is bas ed on three facts. Rings of C-Della-l-expressing fibroblasts precede a nd delimit the forming feather primordia. C-Delta-1 is uniformly expre ssed in the dermis of the scaleless mutant, which is almost entirely d evoid of feathers. Feather development is inhibited by overexpression of C-Delta-1 in wild type dermis using a retroviral construct. We also show that the distribution of C-Delta-1 in the mutant dermis can be r escued by its association with a wild type epidermis, which acts as a permissive inducer, or by epidermal secreted proteins like FGF2. (C) 1 998 Elsevier Science Ireland Ltd.