Circadian variability of kinetics in a transplantable islet-cell tumor of the golden hamster.

The kinetics of a transplantable islet-cell tumor known to secrete paranormal hormonal compounds without any influence of usual regulatory mechanisms was studied in the golden hamster. It was found that during the 42nd diurnal period of growth, labelling and mitotic indices (peaks at midday), mean grain counts (lower at 4 a.m.