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Modelling the mosaic organization of rod and cone photoreceptors with a minimal‐spacing rule
Author(s) -
GalliResta L.,
Novelli E.,
Kryger Z.,
Jacobs G. H.,
Reese B. E.
Publication year - 1999
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.1999.00555.x
Subject(s) - mosaic , cone (formal languages) , physics , biology , computer science , algorithm , geography , archaeology
The mosaic of photoreceptors is regarded as a prime example of the precise control of cellular positioning in the vertebrate nervous system. This study was undertaken with the idea that understanding the intrinsic geometrical features of photoreceptor mosaics is a necessary step to unveil the biological mechanisms governing their formation. We show in the retina of the ground squirrel that the arrays of both the rods and S cones are non‐random, but that nothing more than a simple minimal‐spacing rule constraining receptor positioning is sufficient to account for the spatial organization of both mosaics. The size of this ‘exclusion zone’ is an intrinsic characteristic of each cell type, and it is simply the difference in the size of this domain that accounts for the regularity of the S cone array and the irregularity of the rod array at identical density. Consequently, regularity in receptor mosaics is produced by two independent biological events, one embodying the exclusion zone, and another specifying the local density of a given receptor type.