The capacity of the flank somatic mesoderm of early bird embryos to participate in limb development

Abstract

When prospective limb mesoderm is implanted into the prospective flank of another embryo, a supernumerary limb develops on the flank of the host. Three different criteria by which the presence of host cells could be ascertained within the extra limb have been used, namely, labeling of the graft with 3H-thymidine for the study of its evolution during the first 2 days after implantation, distinctive nuclear feature of implanted quail cells for the study of histogenetic steps 2 and 3 days later, and finally specific distinctive integumentary characters for the study of late organogenesis between 13 days of incubation and hatching. By these means prospective nonlimb flank cells of the host have been demonstrated to participate in the outgrowth, the histogenesis, and the organogenesis of the extra limb.