Remodeling of second-order neurons in the retina of rd/rd mutant mice.

This is a brief review of data obtained by analyzing the morphology and the physiology of the retinas in rd/rd and normal, wt mice, aged 10-90 days. Second-order neurons of the rd/rd show abnormalities that start with the anomalous development of rod bipolar cells around P10 and culminate with the atrophy of dendrites in cone bipolar cells, mostly evident at P90. Horizontal cells remodel considerably. Cone-mediated ERGs, (recorded between 13 and 16 days of age) have reduced a-wave and b-wave amplitudes and longer b-wave latency and duration. B-wave abnormalities indicate specific postreceptoral dysfunction. Morphological and ERG changes in rd/rd retinas are consistent with substantial inner retinal remodeling associated to photoreceptor degeneration.