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Rod photoreceptor maturation does not vary with retinal eccentricity in mammalian retina
1Department of Ophthalmology, University of Florida, Gainesville 32610-0284, USA. atimmers@eye1.eye.ufl.edu
Purpose:
Test the hypothesis that the development of mammalian rod outer segments (ROS) varies with retinal eccentricity.
Methods:
During the period of photoreceptor cell development, ROS lengths, opsin mRNA and (rhod)opsin were measured in central and peripheral retina of cows and pigmented rats. Published ROS length and/or rhodopsin data from albino rats, cows and monkeys were re-analyzed. Logistic growth curves were fitted to the newly obtained and published data. Within a species, growth in central and peripheral regions was compared.
Results:
The logistic growth curves fit all the data well and provide an excellent view of the developmental increases in ROS length, opsin mRNA and (rhod)opsin in each retinal region. Within a species, the growth curves for ROS length, opsin mRNA and (rhod)opsin concentration are superimposable. The age at which ROS length reaches 50% of its adult value is invariant with eccentricity. An exception to this pattern is the simian parafoveal ROS, which appears to have a delayed course of development.
Conclusions:
The hypothesis is disproved. Unlike rod photoreceptor cell genesis, ROS development is invariant with retinal eccentricity. Primate parafoveal ROS appear to have a different pattern of development.