Autoradiographic evaluation of vitamin A effects on Triturus alpestris blastema cells

Autoradiographic studies on Triturus alpestris regenerates treated with vitamin A palmitate for 4, 7, 11 and 14 days after amputation, reveal a considerable diminution in the percentage of cells duplicating DNA, as judged by measurements of labelling indices. Based on previous observations, that vitamin A promotes DNA-synthesis, mitosis and growth of regenerates, we conclude that the lower labelling indices calculated are due to an acceleration of S-phase processes, resulting in a concomitant reduction in its duration.