Shedding is correlated with disk membrane axial position rather than disk age in Xenopus laevis rod outer segments

Disk membrane synthesis and displacement rates in Xenopus laevis retinal rod outer segments, as measured by light-dark dependent birefringence band periods, are proportional to incubation temperature. Outer segment length, however, is approximately the same for frogs raised at different temperatures. Therefore the age of disks shed from outer segment distal tips is a function of temperature. Unless the rate of disk synthesis coincidentally has the same temperature dependence as putative disk membrane aging processes, this implies that position on the outer segment axis rather than disk age is a sufficient condition for disk membrane shedding in Xenopus laevis maintained under diurnal light-dark conditions.