Fig. 3.

Pineal rhythmicity is similar in vivo and in vitro. Reporter construct activity was assayed from explanted pineal glands, either acutely at different times in the light cycle (open bars; mean ± SEM;n = 4 at each time point) or from cultured glands in continuous darkness (filled circles;n = 6). Bioluminescence profiles from cultured pineals were normalized to their peak emission. Acute and continuous measurements peaked ∼3 hr before light onset.