Enhanced labeling of mitotic retinal cells with an intraocular [3H]thymidine injection.

Tritiated thymidine ([3H]Tdr) was injected either intraocularly (i.o.) or intraperitoneally (i.p.). Autoradiography showed that more retinal cells were labeled by i.o. than by i.p. injection. Controls showed that the increased number of labeled retinal cells was not related to glioblast proliferation produced by trauma from the i.o. injection. After injection of identical doses, the peak concentration of [3H]Tdr available for incorporation into DNA was about 100 times greater after an i.o. than after an i.p. injection. The effective duration of the labeling pulse in goldfish was 9 times longer for an i.o. than an i.p. injection. This study shows that i.o. delivery of [3H]Tdr is preferable to i.p. injection for efficient delivery of label to proliferating retinal cells.

Asymmetric distribution of cells in the inner nuclear and cone mosaic layers of the goldfish retina.

Cell counts in hematoxylin-stained, flat-mounted retinae revealed that the inner nuclear (INL) and cone mosaic layers (CML) of the goldfish retina contained a high density of cells along the temporal boundary between dorsal and ventral retina. Our findings indicate that the goldfish contains a region situated in the temporal retina in which the density of a wide variety of cell types, that span several retinal layers, is elevated. This study indicates that the dorsotemporal retina, which is the first retinal region to develop, contains the highest density of cells.