Analysis of morphogenesis and keratinization in transfilter recombinants of feather-forming skin

Abstract

The relationships between feather morphogenesis, histogenesis, and biochemical differentiation were examined by recombining backskin epidermis and dermis, from chick embryos (Hamburger-Hamilton stages 27–31), with an intervening Nucleopore filter (pore size of 0.4 μm). The filter inhibited normal feather morphogenesis and histogenesis of barb ridges, yet feather-like filaments, which were free of dermal cells, formed from the epidermal cells. Using indirect immunofluorescence, with antiserum against α- and β-keratins, the biochemical differentiation of the feather-like filaments was compared to normal feathers. In the feather-like filaments resulting from tissues of stages 27–29, cells containing beta keratins were occasionally seen at the periphery of the filaments, yet cells containing α-keratins were inappropriately located throughout the filaments. In a few feather-like filaments on recombinants resulting from tissues of stages 29.5–31, cells positive for β-keratins were found in the center of the filament, but again α-keratins were also found. Surrounding these cells there were several layers of cells, arranged circumferentially, resembling sheath cells. Some sheath-like cells contained β-keratins. We conclude that although feather epidermal cells, which are separated from their dermis by a Nuclepore filter, can undergo limited morphogenesis and the production of α- and β-keratins, normal feather morphogenesis, histogenesis, and biochemical differentiation require the intimate associations of epidermis and dermis.