Temporo-nasal asymmetry in the accretion of retinal ganglion cells in late larval and postmetamorphic Xenopus.

The spatial pattern of cell production and retinal growth were studied in Xenopus between stage 60 and two months after metamorphosis using 3H-proline and 3H-thymidine autoradiography. The position and the number of the ganglion cells labelled with 3H-thymidine were determined. The area of the unlabelled retina due to growth since 3H-proline administration at stage 60 was measured. Both retinal area measurements and counts of labelled ganglion cells showed 30-40% higher values in the temporal than in the nasal retinal half. The greater cell production and area accretion were even more pronounced between the temporal and the nasal retinal quadrants. The results on the temporoventral crescentic retinal growth rule out the possibility that from midlarval stages onwards the retinal and the tectal growth patterns are matched.