6-H3 thymidine uptake in the central nervous system of newt following lesion and cold shock.

The uptake of 6-H3 thymidine in the optic tectum and the forebrain of the newt following injury to one of the two nervous areas, shows a marked proliferative response in the telencephalon in the presence of a lesion on the right optic tectum, and a poor response of the optic tectum after a lesion on the right telencephalic lobe. A similar proliferative response is also obtained when the specimens received only the cold shock. In both experimental conditions maximum uptake is obtained after 7 days. It is assumed that the matrix cells of the forebrain and the undifferentiated cells of the optic tectum respond differently to the regeneration factor released by the nervous tissue following a lesion or a cold shock.