Non-randomness in the sequential formation of principal cones in small areas of the developing chick retina.
Systematic variation in the stage of development within small retinal areas could account for the overlap between the times of formation of the receptor types in the chick retina. The distributions of unlabelled and labelled principal cones in maps of the receptor mosaic, constructed from retinae exposed to tritiated thymidine during incubation, were analysed by grid analysis (Greig-Smith, '64) and by two computer programmes. The computer programmes were generally more successful than grid analysis in detecting contagion in the distribution of unlabelled and labelled principal cones in the receptor maps. The contagion has been interpreted as evidence that the stage of development varies systematically in small retinal areas and that the overlap between the times of formation of the receptor types may be absent amongst small groups of cells.
D000818:Animals; D002642:Chick Embryo; D003201:Computers; D010786:Photoreceptor Cells / Q000196:embryology*