The ability of localized implants of whole or minced dermis to disrupt pattern formation in the regenerating forelimb of the axolotl.

The ability of localized grafts of dermis to alter pattern formation in the regenerating limb of the axolotl was studied. Longitudinal pieces of skin (1/4 of circumference of the limb) were removed from either the anterior or the posterior surface of the upper forelimb. Epidermis was removed by immersion in versene followed by mechanical stripping. The resulting dermis was cross transplanted directly beneath the skin on the opposite side of the limb from which it originated. After 5 days of healing each limb was amputated through the graft at the midpoint of the humerus. High percentages of multiple regenerates resulted. Similar results were obtained when dermis was minced into 1 mm3 fragments prior to cross-transplantation. Freezing or x-raying (2000 rads) the grafts prior to cross-transplantation abolished the effect. Dermis obtained form head skin rarely caused multiple regeneration when implanted into the upper forelimb followed by amputation 5 days later. These results demonstrate that addition of dermis to an intact limb stump profoundly alters pattern formation during regeneration. The effect is dependent upon viable cells that are capable of cell division.