Figure 3.

Persistence of photoperiod history effect did not vary as a function of the duration of 15L treatment in individuals that acquired a photoperiodic history. (a) Mean (± SEM) ETV of hamsters that manifested testicular regression in 13.5L (data are replotted relative to the week animals in each group were returned to 13.5L). Groups did not differ in the timing of the onset of recrudescence (ANOVA, P > 0.30). Symbols indicate that the LD-0 mean differs significantly from that of other groups: *, P < 0.05 vs. all other groups; #, P < 0.05 vs. LD-2, LD-4, and LD-8; §, P < 0.05 vs. LD-1, LD-8, and LD-12; †, P < 0.05 vs. LD-1, LD-2, LD-8, and LD-12. (b) Simple regression reveals essentially no correlation (R² = 0.01) between the duration of 15L exposure and the week of onset of testicular recrudescence in 13.5L; photoperiodic histories encoded by longer intervals of 15L exposure did not differ from those encoded by shorter 15L treatments.