Different phenotypic characteristics of WT and Tg rats at ages up to P365. The values are expressed as a percent of control (WT), shown as a dashed line. The P23H lines (AC) and S334ter lines (D–H) are each arranged in descending order of PR degeneration rate, with the most rapidly degenerating given first. ONL, solid line; X, ONL of homozygote; ROS length, shaded bars; whole-eye rhodopsin, open circles. ERG amplitudes in each of the Tg rat lines up to P365 or until the waves are extinguished. Scotopic a-wave (blue line); scotopic b-wave (green line); photopic b-wave (red line). The amplitudes are in response to saturating stimuli. The most rapidly degenerating lines, S334ter-7 and S334ter-3, showed no ERG responses. The values are the means of 3–5 rats at each age. The scotopic b-waves shown are from stimuli presented at an intensity of 0.4 log cd-s/m2, followed by a stimulus at 2.4 log cd-s/m2 to elicit the scotopic a-wave. The rats were then exposed to a background light of 29 cd/m2 for 10 minutes before they were exposed to stimuli of 0.4 log cd-s/m2 to elicit the photopic b-wave. The error bars have been omitted for clarity. As noted in the legend to Fig. 1, the variance in the raw data upon which these percent of control values were calculated was small for the ONL, most being <1.0 mμ and all but one being <2.0 mμ. The SEMs of all of the rhodopsin and rod outer segment lengths after P10 were mostly <1.0 mμ, with a few <2.0 mμ. The ERG measurements were intrinsically more variable, but the SEMs were still mostly <20.0 μV, with almost all <40μV.