RETINAL GANGLION-CELL DENDRITIC DEVELOPMENT AND ITS CONTROL - FILLINGTHE GAPS

The way in which central neurons acquire their complex and precise den drite arbors is of considerable developmental interest. Using retinal ganglion cells (RGCs) as a model, the mechanisms that pattern dendriti c development are beginning to emerge. As in other systems, final dend rite phenotype is achieved by a mixture of intrinsic and extrinsic det erminants. The extrinsic determinants of RGC dendrite shape reflect th e anatomical constraints of producing a paracrystalline mosaic of arbo rs that laminates the inner plexiform layer of the retina. In this art icle, the key features of RGC dendrite development are reviewed. The e merging molecular mechanisms behind dendritic laminar segregation and ''dendritic competition'' are described. The role of afferent extrinsi c influences are contrasted with those of retrograde, activity-depende nt target influences that may regulate the final maturational phase of dendrite remodeling.