Regeneration of whole limbs in toad tadpoles treated with retinol palmitate after the wound‐healing stage

In young Bufo melanosticus tadpoles at the spatula stage of limb development, the left hindlimb was amputated through the shank and the right hindlimb was left intact. One day later, when the amputation surface was covered by wound epidermis, the tadpoles were immersed in 15 IU/ml of retinol palmitate solution for 2 days up to blastema formation and thereafter reared in plain water. Contrary to the situation in untreated controls, all the resultant regenerates of the vitamin‐treated tadpoles were complete limbs containing elements from the pelvic girdle to the phalanges. Retinol palmitate treatment inhibited the development of the foot in the unamputated right limbs. These results show that retinol palmitate has a different effect on dedifferentiating cells of a regenerating limb from that on cells that are differentiating in a normally developing limb.