Immunofluorescent localization of collagen types I and III, and of fibronectin during feather morphogenesis in the chick embryo

Abstract

Collagen types I and III were purified from the skin of 3- or 7-week chickens and fibronectin from human serum. Antibodies were raised in rabbits and used in indirect immunofluorescence on frozen sections of 5- to 16-day chick embryo feather-forming skin. Prior to the formation of dense feather-forming dermis, anticollagen fluorescence was confined to a thin underlining of the dermal-epidermal junction (DEJ), while antifibronectin label was retained on loosely dispersed material in the predermal mesenchyme. Dense feather-forming dermis was characterized by loosening of the anti-collagen label along the DEJ, by its spreading throughout the thickness of dermis, and by an overall densification of antifibronectin label. Feather formation coincided with a decrease of anti-collagen and an increase of antifibronectin label density in the dermal feather condensations and in the core of outgrowing feather buds. By contrast, density of anti-collagen-labeled material was highest and anti-fibronectin-labeled material was lowest in interplumar and glabrous skin. In slanting feather buds and feather filaments, distribution of anti-collagen-labeled material exhibited a type-specific cranial-caudal asymmetry. The microheterogeneous distribution of extracellular matrix components might constitute part of the morphogenetic message that the dermis is known to transmit to the epidermis during the formation of cutaneous appendages.