Reorganization of horizontal cell processes in the developing FVB/N mouse retina

We investigated the morphological changes of horizontal cells after postnat al photoreceptor degeneration in the developing FVB/N mouse retina, using i mmunocytochemistry with anti-calbindin D-28K. From postnatal day 14 (P14) o nwards, processes emerging from horizontal cells descend into the inner ple xiform layer (IPL) and ramify mainly in stratum 1 of the IPL. Electron micr oscopy revealed that the descending processes make synaptic contacts with b ipolar cells in the outer plexiform layer. Our results clearly demonstrate that loss of photoreceptor cells induces the reorganization of horizontal c ell processes in the retinas of FVB/N mice as they mature.