Study on nucleic acid synthesis in mouse retina and retinal pigment epithelium by radioautography

The ocular tissues of ddY mice from embryonic 9 to postnatal day 14 were labelled in vitro with 3H-thymidine or 3H-uridine. After radioautography, the radioautographs were observed by light and electron microscopes. The labeling indices (L.I.) with 3H-thymidine or grain numbers with 3H-uridine were calculated and the area (microns 2) of cell organelles in both labelled and unlabelled retinal cell with 3H-thymidine were measured by image analysis. The L.I. of retinal cells were low in the beginning then increased and reached a peak at P3, while the L.I. of retinal pigment epithelium (RPE) increased and reached a peak at P7. The L.I. of both retinal and PE cells disappeared at P14. However, the L.I. of anterior region were more than those of equaterial and posterior regions in both retinal and PE cells. The results of the image analysis showed that the average area of cell organelles, both labelled and unlabelled retinal cells decreased from E9 to P14. The grain numbers of retina labelled with 3H-uridine increased until P1 then decreased, while the numbers of RPE increased and reached a peak at P3 whereafter they declined. No significant differences were detected among the three regions.