Local application of retinoic acid to the chick limb bud produces effects that are dose and/or stage dependent. Low doses and/or old stages tend to give normal limbs or perhaps one or two supernumerary digits of a more anterior character. Medium doses and/or intermediate stages tend to give full mirror-image supernumeraries with two or even three extra digits including particularly digits of a ...

EXPERIMENTALLY produced functioning reduplications, triple and quintuple hindlimbs of the frog have not yet been described. Supernumerary limbs can be produced either by transplantation methods or by the methods described in this paper. In order to prevent confusion between a reduplication of the primordium itself and a doubling after orthotopic transplantation of a limb bud, the author disting...

Previous studies showed that grafting wedges of fresh or cultured anterior quail wing mesoderm into posterior slits in chick wing buds resulted in the formation of supernumerary cartilage in a high percentage of cases. When anterior quail mesoderm, which had been dissociated into single cells and pelleted by centrifugation, was grafted into posterior slits of host chick wing buds, supernumerary...

PREVIOUS studies on the transplantation of limbs in the embryo of Eleutherodactylus martinicensis have shown that supernumerary limbs tend to be less well innervated than are corresponding replacing grafts, and that the innervation of the former, either autografts or homografts, is progressively less extensive with increase in time after operation. The degree to which grafted supernumerary fore...

The model proposed in the preceding paper (Meinhardt, 1983) makes specific predictions about the handedness of supernumerary limbs generated after 180 degrees rotation of blastemas. These predictions are tested here by re-examining, in detail, the structure of 100 of these supernumeraries. Of the four predictions, only one was found not to hold. The other three are remarkably precise in their p...

PREVIOUS studies on the transplantation of limbs in the embryo of Eleutherodactylus martinicensis have shown that supernumerary limbs tend to be less well innervated than are corresponding replacing grafts, and that the innervation of the former, either autografts or homografts, is progressively less extensive with increase in time after operation. The degree to which grafted supernumerary fore...

PREVIOUS studies on the transplantation of limbs in the embryo of Eleutherodactylus martinicensis have shown that supernumerary limbs tend to be less well innervated than are corresponding replacing grafts, and that the innervation of the former, either autografts or homografts, is progressively less extensive with increase in time after operation. The degree to which grafted supernumerary fore...

Synpolydactyly (SPD) is a distal limb anomaly characterized by incomplete digit separation and the presence of supernumerary digits in the syndactylous web. This phenotype has been associated with mutations in the homeodomain or polyalanine tract of the HOXD13 gene. We identified a novel mutation (G11A) in HOXD13 that is located outside the previously known domains and affects the intracellular...