Supernumerary Limb Induction in Ambystoma Larvaeby Frog Tissue Implants

Abstract

Pieces of kidney and/or lung from adult frog (Rana pipiens) when implanted under the dorsal skin of the lower arm (mid-radius/ulna level) of Ambystoma maculatum larvae, induced supernumerary limbs in over 75% of the cases. Liver was completely ineffective in inducing ability. However, liver did not lower the inducing capacity of lung in combination grafts. When the insertion hole was distal to the graft, the percentage of induction by kidney was slightly higher than when the insertion hole was proximal. In each case, the supernumerary limb developed from the site of the insertion hole. The original epidermis covering the insertion injury site very likely became the wound epidermis for the supernumerary regenerate. In comparison to frog kidney, newt (Notophthalmus viridescens) kidney was a poor inducer. Limbs with Ambystoma cartilage grafts or limbs simply injured without tissue implants did not exhibit supernumerary limb induction.