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Determinants of the exclusion zone in dopaminergic amacrine cell mosaics
Author(s) -
Raven Mary A.,
Eglen Stephen J.,
Ohab John J.,
Reese Benjamin E.
Publication year - 2003
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.10693
Subject(s) - amacrine cell , dopaminergic , biology , neuroscience , retina , retinal , dopamine , biochemistry
A fundamental organizing feature of the retina is the presence of regularly spaced distributions of neurons, yet we have little knowledge of how this patterning emerges during development. Among these retinal mosaics, the spatial organization of the dopaminergic amacrine cells is unique: using nearest‐neighbor and Vornoi domain analysis, we found that the dopaminergic amacrine cells were neither randomly distributed, nor did they achieve the regularity documented for other retinal cell types. Autocorrelation analysis revealed the presence of an exclusion zone surrounding individual dopaminergic amacrine cells and modeling studies confirmed this organization, as the mosaic could be simulated by a minimal distance spacing rule defined by a broad set of parameters. Experimental studies determined the relative contributions of tangential dispersion, fate determination, and cell death in the establishment of this exclusion zone. Clonal boundary analysis and simulations of proximity‐driven movement discount tangential dispersion, while data from bcl‐2 overexpressing mice rule out feedback‐inhibitory fate‐deterministic accounts. Cell death, by contrast, appears to eliminate dopaminergic amacrine cells that are within close proximity, thereby establishing the exclusion zone surrounding individual cells and in turn creating their mosaic regularity. J. Comp. Neurol. 461:123–136, 2003. © 2003 Wiley‐Liss, Inc.