Skull Development in Chick Embryos after Ablation of One Eye

Abstract

THERE is in birds a thin vertical plate of bone between the eyes known as the interorbital septum. In the chick embryo this originates from the fusion of two pairs of cartilaginous primordia (the orbital cartilages above and the trabeculæ cranii below) with each other and with a median cartilaginous bar, the intertrabecula. At around seven to eight days of incubation, these structures lose their identities and merge into one another to form the high thin septum of the fully formed chondrocranium. At about the same time the lateral unfused parts of the anterior orbital cartilages regress and disappear almost completely.