A precise, sequential staining procedure which demonstrates sulfated and non-sulfated mucopolysaccharides and glycogen in the urodele forelimb is described. The process, a combination of the alcian and PAS techniques, has proven valuable in following histogenic events during forelimb regeneration. Non-sulfated mucopolysaccharides are present in apical cap epithelium, sarcoplasm, and bone matrix. Both alcian blue and PAS responses are apparent in dedifferentiating cartilage. Glycogen was apparent in late blastema cells, mature and to a lesser extent in maturing muscle, and wound epithelium.

This study shows that streptomycin has both the non-specific effect, short of toxicity, of disrupting developmental sequences in larval anurans and the phase specific effect of altering tail fin regeneration. Streptomycin seems to inhibit regeneration of mesenchymal elements while leaving ectodermal components able to proliferate though in quantitatively different amounts. It appears, therefore, that the regressive, histolytic stages of regeneration are not significantly affected by streptomycin, but the phases of cytoredifferentiation of muscle and connective tissue amounts and the regulation of somite pattern are progressively curtailed with exposure to the drug.

Quantitative extraction, histological, and histochemical procedures were used to investigate the effects of the stress of forelimb amputation on liver metabolites in the adult newt, D. viridescens. Results of these experiments showed that hepatic PAS responsive stores were depleted two hours through one week after amputation while protein decreased 24 hours -one week after amputation. There was no change i n hepatic lipid. Hepatic GLU 6-PDH and a-glucan phosphorylase activities increased almost immediately after limb amputation and did not return to normal until one week and two weeks later, respectively. These and previous experiments suggest a systemic response to forelimb amputation whereby liver metabolites may initially provide energy reserves for escape and survival and then contribute to the early phases of regeneration.

Histone hydrolase activity was measured spectrophotometrically during the first 26 days of forelimb regeneration in the adult newt. Enzyme activity was low during wound healing but substantially increased 11–15 days after amputation (i.e. dedifferentiation). The enzyme is primarily localized in the cytosol. It has a pH optimum of 6–7 and is highly reactive against basic proteins.