[Experimental gerontologic transversal examination of rat blood cells paying special regard to daily variations...

Four groups of Sprague-Dawley rats aged 8, 13, 28 and 33 months were allowed to participate in this investigation of RBC, volume distribution of red cells and differential leukocyte count as function of age. Furthermore, the authors examined whether daily variations of these parameters should be taken into account. The RBC decreases and the cell volume increases with age. The differential lymphocyte count (%) declines, whereas the differential neutrophile count (%) increases. Because of the small amplitudes of the erythrocyte parameters daily variations can be ignored. The white blood cell counts show considerable daily variations in young and old rats. These variations do not exert influence on the differential blood cell counts (%) because they are equal in phase and period. Daily variations must be taken into account when absolute values are calculated from these results.