Regeneration of whole limbs from shank level blastema grafted autoplastically in the orbit in the toad tapoles immersed in vitamin A solution following first amputation

Abstract

Earlier studies showed that in young toad tadples immersed in 15 I.U. /ml vitamin A palmitate solution for 3 days following hind limb amputation the resultant blastema possessed greater than usual morphogenetic capacity and differentiated into whole limb instead of only the distal, actually removed portion. Results of the present study demonstrate that this enhanced capacity is inherent in the blastema developed in the so treated tadpoles and is manifested even if the blastema is grafted ectopically far from the stump. In young 30/31 stage tadpoles of the toad Bufo melanostictus treated as above following amputation through shank the 3 days old blastema was cut out by a second amputation through its base and autoplastically grafted into the left orbit enucleated about 12 hours earlier by removal of the eyeball. Care was taken to exclude any portion of the stump while isolating the blastema. The tadpoles were kept immobile for a few hours after this operation to allow the graft to heal into the orbit. And then transferred to the tap water for the next 12 days. Control tadpoles were subjected to similar operations but did not receive any treatment with vitamin A. Out of 20 control grafts 14 were taken and among them 12 formed analyzable regenerates. All of them consisted of only autopodial segment with 2 - 4 toes and contained differentiated skeletal elements, muscle fibres and adult type skin. In the treated group, out of 20 grafted blastemas 10 were taken and 8 of them formed regenerates which could be analyzed. They were small and histologically less differentiated than those of controls but each regenerate was a whole limb consisting of stylopodium, zeugopodium and autopodium.