Functional activity of the suprachiasmatic nuclei in the fetal primate.

The [14C]labeled deoxyglucose method was used to monitor the daily pattern of glucose utilization in the suprachiasmatic nuclei of the squirrel monkey during late fetal development. The findings suggest that a circadian clock is functioning prenatally in the primate suprachiasmatic nuclei and that the maternal circadian system coordinates the timing of the fetal clock to ambient lighting.