Fig. 1.

In rats living in an enriched environment, the numbers of proliferating cells in the SGZ and GCL identified by BrdU-labeling was dependent on the time of BrdU administration within the light-dark cycle. Labeled cell counts were significantly higher after BrdU administration at ZT9 and animals were sacrificed at ZT11, at the end of the light phase of the light-dark cycle. There was no significant effect of circadian time on labeling in the hilus. ** P < 0.01.