Delayed Denervation and Accessory Limb Formation in Urodeles

Abstract

FROG kidney adenocarcinoma implants and normal adult frog kidney implants made subcutaneously on the dorsal radioulnar surface of non-regenerating larval salamander forelimbs cause the host limbs to respond to their presence by forming supernumerary hand-wrist structures. Larval host limbs may on occasion fail to elicit any morphological response¹. On the other hand, adult salamander host limbs may form: (a) an accessory structure comparable with the larval response; (b) nothing; (c) single or clustered subcutaneous cartilaginous nodules as in Fig. 1 ^2,3. Although these nodules are commonly found in adult host limbs, they had never been produced by larvae in hundreds of cases assayed.