Light-triggered rod disc shedding in Xenopus retina in vitro.

The present study was designed to determine whether light-induced rod outer segment disc shedding occurs when the eye is isolated from the rest of the organism. Whole eye explants of Xenopus laevis were maintained in vitro and either exposed to 5 min of light or kept in darkness. In both the in vitro eyes and in vivo controls exposed to the same conditions, a significant degree of disc shedding occurred within 1 hr of the light stimulus. The disc shedding response was larger in the explanted eyes than in the intact animals. In explants exposed to [3H]leucine for 24 hr, a radioactive band formed at the base of rod outer segments. Thus both light-stimulated disc shedding and disc synthesis occur in the eye kept in vitro. The results of this study are compatible with other recently reported results suggesting that rod disc shedding is initiated within the eye.