Circadian Periodicity of Bone Marrow Mitotic Activity and Reticulocyte Counts in Rats and Mice

Abstract
Mitotic proliferation in the bone marrow of female rats and mice kept under standardized coniditions with light from 6:00 a.m. to 6:00 p.m. exhibited a significant circadian periodicity with the greatest activity occurring from 6:00 a.m. to 12:00 noon. The reticulocyte levels in peripheral blood were highest at 8:00 a.m.