Vitamin - a and limb regeneration in stages of the egyptian toad, bufo regularis Reuss-histological study
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The histogenesis of regenerated limbs, of both control and treated /larvae/ with 30 I.U./ml of retinol palmitate for 3 days, was studied in two larval stages (viz. stages 53 & 54) of the anuran amphibian, Bufo regularis Reuss. Some histological changes took place in the amputated limbs of treated larvae in two phases: (a) during treatment and (b) after cessation of treatment and thereafter. In (a): the wound epidermal superficial layer became corrugated, basement membrane was not discernible, local haemorrhage was extensive and blastema call accumulation was inhibited. In (b): the epidermal surface maintained its irregularity for some days and contained numerous large vocuolated cells. Also, cells from the dedifferentiated stump tissues underwent active proliferation leading to the establishment of a large blastema, particularly in the case of the earlier stage. Cellular condensations in these blastemas were mostly unevenly distributed; they appeared more closely packed together posteriorly than anteriorly along the antero-posterior axis. Histological observations concerning blastema cells and theair active proliferation after cessation of treatment, were confirmed quantitatively through the blastema volume in both stages.