Rod photoreceptor maturation does not vary with retinal eccentricity in mammalian retina

Purpose. Test the hypothesis that the development of mammalian rod outer se gments (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 o f 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 ex cellent 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. Th e 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, wh ich appears to have a delayed course of development. Conclusions. The hypothesis is disproved. Unlike rod photoreceptor cell gen esis, ROS development is invariant with retinal eccentricity. Primate paraf oveal ROS appear to have a different pattern of development.