title: The time required for positional signalling in the chick wing bud.
abstract: An estimate of the time required for positional signalling in the chick wing bud was obtained by grafting irradiated quail polarizing regions to host wing buds and removing them at various times. Such polarizing regions must be present for at least 15 h to induce additional structures in the host wings. This results is discussed in terms of a diffusible morphogen model.
mesh_terms: D000818:Animals; D002642:Chick Embryo; D005720:Gamma Rays; D011784:Quail / Q000196:embryology; D013997:Time Factors; D014183:Transplantation, Heterologous; D014921:Wings, Animal / Q000196:embryology* / Q000528:radiation effects / Q000637:transplantation