Embryonal feather growth in the chicken

Prenatal feather growth development in the chicken was studied in 7 body re gions in HH stages 27-45, using direct measurements, specific histological and immunohistochemical methods, and scanning electron microscopy. The resu lts from measurements of absolute length values, and, particularly, growth rate development in each HH stage revealed a distinct phase of most intensi ve growth in HH stage 40-41, which was preceded by feather follicle inserti on and accompanied by the occurrence of alpha-keratins in barbule cells. Sp ecific regional evaluation demonstrated that growth in the feather follicle s of abdominal skin generally showed the slowest progression from absolute values and that in the feather filaments of the developing wings the most r apid progression occurred during HH stage 40-41 from growth rate values.