Fig. 1. Origin and contribution of dermal bone in cranial skeletal development. (A) Contribution of cranial neural crest cells (orange) and mesoderm (grey) to the cartilage (blue) and bone (red) components of the avian skull (see also Noden, 1986; Couly et al., 1993). Notice the heavy contribution of neural crest to the cranial dermal bones. (B) Bone mineralization in E9-E13 chick embryonic heads as revealed with alizarin red stain. dnt, dentary bone; ep, epidermis; fnt, frontal bone; nt, neural tube; pmx, pre-maxillary bone.