Table 1.
Treatments in each phase (photoperiod or surgery) and the number of hamsters that did (Regr.) or did not (No Regr.) exhibit testicular regression. In experiment 3, phase 2, hamsters remained in their phase 1 photoperiod after pinealectomy (pinx) or sham-pinx. Chi-square tests compared the proportion of Regr. hamsters in a given group with the within-experiment control group.
| Phase 1 Treatment | Regr. | No Regr. | Phase 2 Treatment | Regr. | No Regr. | Chi-Square Test | |
|---|---|---|---|---|---|---|---|
| Experiment 1 | 16L | 0 | 20a | 10L | 10 | 16b | Control |
| LL | 22 | 24c | 10L | 2 | 20 | p < 0.05 | |
| Experiment 2 | 16L | 0 | 14 | 10L | 6 | 8 | Control |
| 10L | 9 | 1c | 10L | 0 | 9 | p < 0.05 | |
| Experiment 3 | 16L | 0 | 34 | Pinx in 16L | 8 | 14 | Control |
| Sham in 16L | 0 | 12 | p < 0.05 | ||||
| 10L | 29 | 6c | Pinx in 10L | 0 | 17 | p < 0.01 | |
| Sham in 10L | 1 | 11 | |||||
| Experiment 4 | 16L | 0 | 11 | LL | 5 | 6 | Control |
| 10L | 12d | 2d | LL | 0 | 9 | p < 0.02 |
a
ETV was not measured for 7 hamsters in phase 1.
b
One hamster died after 4 weeks of phase 2.
c
Nonresponders were removed from phase 2 analyses.
d
Three responders and 2 nonresponders were removed for a separate experiment before phase 2.