Optic nerve crush modulates proliferation of rod precursor cells in the goldfish retina

Tritiated thymidine ([ 3H]TdR) autoradiography revealed a correlation between the rate of cell proliferation of rod precursor cells in the outer nuclear layer (ONL) of the goldfish retina and the postoperative interval after crush of the optic nerve (ONC). Ten days after unilateral ONC there were more labeled nuclei in the ONL of the nerve-crushed retina than in the intact, contralateral retina of the same fish one day after single bilateral intraocular injections of [ 3H]TdR. From 15 to 25 days after ONC, however, fewer labeled nuclei were found in the ONL of nerve-crushed retinae than in controls, illustrating a decrease in the number of cells entering the S-phase of the cell cycle; by 35 days the differences had disappeared, demonstrating that cell birth recovered to normal. When examined one month after [ 3H]TdR injection, fewer labeled cells were present in the nerve-crushed retina at all postoperative intervals. Examination of the numbers of labeled cells at various postoporative periods following bilateral ONC, when one retina was examined one day and the other retina was examined one month after [ 3H]TdR administration revealed that the ratios of labeled cells between the two retinae varied as a function of time after ONC. Therefore, optic nerve crush appears to enhance the proportion of initially labeled cells in the ONL that are either fated to undergo further cell generation cycles or to die.