Effect of dorsal and ventral limb ectoderm on the development of the limb of the embryonic chick.

Limb ectoderm plus a small amount of subjacent mesoderm obtained from the dorsal or the ventral surface of each of the four limbs of the chick embryo were grafted to the dorsal surface of the right wing in either reversed or normal orientation. The host wings developed in abnormal humerus in all cases except when the graft was obtained from the dorsal surface of the right wing and was in normal orientation. However, the nature of the abnormalities varied with the source of the graft and with the orientation of the graft. It is unlikely that the abnormalities were related solely to the small amount of mesoderm grafted since previous experiments have demonstrated that the mesoderm would regulate. Flank ectoderm plus a small amount of flank mesoderm did not cause limb abnormalities when grafted in the same manner.