Red cell size as measured by the Coulter model S.

The MCV (mean corpuscular volume) was examined by the Coulter model S. It was found that the MCV measured by the Coulter S was larger than the generally accepted range 82 to 92, or 76 to 96 mu(3). The range in 500 healthy individuals was 82.2 to 100.6 mu(3). It was also found that the mean MCV became larger with increasing age. No sex difference was found. The low MCV by manual methods was generally thought to be attributed to less accurate measurement of erythrocyte counts.