Abstract
The regenerating and stump tissues of amputated forelimbs of the adult newt, Diemictylus viridescens, were analyzed for collagen content and synthesis. Collagen soluble and insoluble in 0.45 M NaCl was assayed by (1) spectrophotometric determination of hydroxyproline, (2) radiotracer determination of ^14^Cβproline incorporation, and (3) radiochromatographic analysis of the ^14^Cβproline/^14^Cβhydroxyproline ratio in the two collagen fractions.
The results obtained reveal that there is significantly less saline insoluble as well as soluble collagen in the regenerating limb tissues than in the basal stump of the amputee, though a soluble fraction is demonstrable throughout the course of regeneration. By ninety days after amputation, there is a significant increase in the insoluble collagen fraction in the regenerating limb.
The soluble collagen fractions assayed in the regenerating tissues are newly synthesized protein, and this synthetic activity appears to be greatest during the paddle and early digitiform stages of regeneration. The soluble collagen extracted from regenerates appears to be less completely hydroxylated with respect to hydroxyproline content than obtains in corresponding fractions from limb stump and control limb tissues.