Uptake of tritiated thymidine in mitochondria of the retina

Light microscopic autoradiography with 3H-thymidine was used as a probe for DNA synthesis on the retinas of the guinea pig, rabbit, and monkey. Relatively heavy labeling was found in the ganglion cell and inner nuclear layers as well as in the photoreceptor inner segments in the guinea pig and monkey. Electron microscopic autoradiography demonstrated that in the ganglion cells and photoreceptor inner segments in the monkey, 89% of silver grains, representing thymidine uptake, were on or near the mitochondria.