title: Morphogenesis and territorial coverage by isolated mammalian retinal ganglion cells.
abstract: Identified retinal ganglion cells were isolated from postnatal cat retinas and their dendrites were removed by trituration and centrifugation. The denuded cells were placed in a cell culture system and allowed to reexpress dendritic arbors in the absence of afferent input, target tissue, and interactions with neighboring ganglion cells. The retinal ganglion cells were grown above a feeder layer of astrocytes on glass coverslips equipped with paraffin pedestals. The spatial patterns of the reexpressed neurites were quantitatively analyzed using a number of measures, including an estimate of the Hausdorff dimension, H, which was used as a scale-independent metric for how well the neurite patterns filled in a restricted spatial domain. As assessed by the estimation of the Hausdorff dimensions, the neurites from a single cell achieve uniform coverage of a restricted territory independent of the total neurite length or the total number of inter-branch-point segments. A comparison with H values of ganglion cells from the intact retina revealed a similar trend. These results suggest that these cultured ganglion cells can express an intrinsic growth strategy for the uniform coverage of a restricted territory. The arbors expressed in the culture system displayed a limited range of diameters and exhibited morphology similar to the alpha-, beta-, and gamma-ganglion cells of the intact retina in the absence of afferent input or the influences of neighboring cells and target tissue. Time-lapse video data revealed that individual cultured cells showed extensive dendritic remodeling during their growth; however, after about 3 d in culture, this remodeling did not appreciably affect the territorial coverage of a cell. In the intact retina, the existence of dendritic sheets that independently and uniformly sample visual space may result from this intrinsic ability to elaborate dendrites that uniformly cover or fill in a restricted territory.
authors.affiliation: Neurobiology Research Center, University of Alabama, Birmingham 35294.
authors.forename: P R
authors.initials: PR
authors.lastname: Montague
authors.forename: M J
authors.initials: MJ
authors.lastname: Friedlander
mesh_terms: D000818:Animals; D001369:Axons / Q000502:physiology* / Q000648:ultrastructure; D002415:Cats; D002478:Cells, Cultured; D046508:Culture Techniques / Q000379:methods; D003712:Dendrites / Q000502:physiology* / Q000648:ultrastructure; D009024:Morphogenesis; D012165:Retinal Ganglion Cells / Q000166:cytology / Q000502:physiology*; D013997:Time Factors