Figure 4

Experiment 2 (ECR): plasma LH concentration measured in bi-weekly blood samples obtained from two pinealectomized Suffolk OVX+E ewes. Animals were maintained melatonin-free under simulated natural photoperiodic conditions in a light-proof building for 2 years. The upper graph depicts LH profiles in one ewe in the High stage of the endogenous rhythm at the end of the experiment and the lower graph LH profile of one ewe in the Low stage. Inserts depict LH pulsatile secretory profiles at the end of the experiment (blood sampled every 6 min for 4 hours).