A study of ocular morphogenesis in the rat using (3H)thymidine autoradiography: evidence for thymidine recycling in the developing retina.

With the use of light microscopic autoradiography, the incorporation and subsequent distribution of [³H]thymidine within the retinas of sequentially staged rat embryos was studied during the period when large numbers of cells become necrotic and were resorbed within the optic rudiment. In the 48 hr following injection of isotope on embryonic Day 11, the number of grains overlying the dorsal, nondegenerate portion of the retina decreased to a low level, whereas ventrally, where the retina becomes intensely necrotic, the grain counts remained at much greater levels. The results indicate that thymidine may be recycled within normally degenerate regions of the embryonic retina.