ABSTRACT
An analysis of the factors in the differentiation of the neoptile feathers of chicken and duck
In the spinal pteryla, the neoptile feather (prepenna) of the chicken differs from that of the duckling by its umbelliform structure, by having few barbs (11 to 14), by its nodose barbules, and by the almost total absence of spines. The prepenna of the duckling is characterized by its well-developed rachis, its numerous barbs (14 to 30), whose barbules are adorned with a double row of spiny barbicels.
The xenoplastic association of dermis and epidermis of 7-to 8-day chick embryo and 8- to 9-day duck embryo results, after 11 days on the chorioallantoic membrane, in the formation of chimaeric feathers, the general macroscopic morphology of which is in conformity with the specific origin of the dermis.
The xenoplastic skin expiants containing duck dermis and chick epidermis develop feathers with a large number of barbs (17 to 21) and a duck-type rachis; the ones that contain chick dermis and duck epidermis grow umbelliform chicktype feathers with a small number of barbs (11 to 14).
The fine structure of the barbules of these chimaerical feathers always differentiates according to the specific origin of the epidermis, as regards the number, distribution and shape of the spiny barbicels.
