Abnormal hind limb regeneration in the tadpoles of the toad Bufo andersonii exposed to vitamin excess

Abstract

Young tadpoles of the toad, Bufo andersoni, at a very early stage of hind limb development underwent amputation through the shanks and were exposed to 15IV of vitamin A palmitate per I ml of water. Whereas controls regenerated normal limbs, in the treated tadpoles the regenerates were retarded and highly abnormal. In 6 out of 14 cases multiple regenerates developed from the stump. In 5 cases the regenerated portion consisted of rudiments of the whole limb including thigh, shank, and foot regions, i.e. also from parts already present in the stump. It is suggested that exposure to excess vitamin A increases the potencies of the blastemas thus enabling them to overcome the restrictive influences of the stump and to form a whole'limb instead of only the distal parts actually removed by amputation.