EFFECTS OF ANIMAL AGE ON THE RESPONSES ALONG THE OUTER SEGMENT OF RETINAL ROD PHOTORECEPTORS

THE aim of the present study was to determine whether the response gra dient, known to exist along a rod outer segment, is influenced by age and developmental changes. Since intense light flashes saturate the re sponses of retinal rods and the time the response remains saturated in creases from base to tip of the rod outer segment, one can use this di fference in saturation times as a measure of the response gradient. Du ring development and before sexual maturity (about one year postmetamo rphosis) the differences between base and tip decreased, and this corr elated with an acceleration of the light response in Xenopus laevis ro ds. The gradient along the rod outer segment then stabilized, while th e response kinetics slowed and remained at a lower level. We conclude that photoreceptor responses and hence visual performance are affected by developmental changes.