Distribution of Size and Shape in Populations of Normal Human Red Cells

Abstract

The diameter, area, and volume of individual human erythrocytes (of 8 subjects, newborn to age 71) were determined by photographing the cells hanging on edge. Measurements from high magnification prints were processed by computer. The distributions of diameter, area, and volume are described statistically, with the unexpectedly linear regression equations for their interrelations. The plot of area vs. volume for the 1016 normal cells from seven subjects (newborn excluded) was remarkably linear with a "straight-line" boundary restricting the distribution. Shape was characterized by a dimensionless "sphericity index" (4.84.volume 2/3 /area). Cells of larger volume tended to be thinner than the smaller cells. The red cell can easily be deformed at constant volume, but an increase in membrane area results in hemolysis. A theoretical geometric parameter, the "minimum cylindrical diameter" (MCDiam), in microns, the thinnest cylindrical channel through which each individual cell could pass, predicts the linear boundary of the plot of area vs. volume. The MCDiam value of 3.66 µ ± 0.04 SEM accurately represents the thinnest channel through which 95% of the cells can pass. In two splenectomized patients with hereditary spherocytosis the MCDiam was increased to approximately 4.0 µ, suggesting that the severest restriction is located in the spleen.

The effect of the red cell membrane and a diffusion boundary layer on the rate of oxygen uptake by human erythrocytes

“…The initial rate of change of saturation is then converted to the initial 02 uptake per cell (Qeell)0, by prcl2"))b [Hb] (dy/dt)o (m -mole 02/(cell sec )), (7) where [Hb] is the amount of haemoglobin per cell (found to be 5-4 x 10-3m-mole per cell for the cells used in these studies). The initial 02 flux per cell (Joel")o is expressed by dividing (Qcell)o by the surface area per human cell (Acell =1-82 x 10-6 cm2: Canham & Burton, 1968): 2= (0 ll)0/Aell (m-mole 02/(cell sec cm2)). (9) It is assumed that at time 0 the PO inside the cell is 0 mmHg.…”

Optical and mathematical corrections of micropipette measurements of red blood cell geometry during anisotonic perifusion

“…In addition, because of the narrow capillaries (3) and slits (15) in the microcirculation, cell geometry is thought to be one of the factors limiting RBC in vivo survival. The minimum cylindrical diameter (MCD), which can be calculated from membrane surface area and cell volume (2,121, represents the narrowest pore or capillary a n RBC can completely enter without loss of volume; for human RBC, the MCD is about 2.8 pm (3,121. Thus, knowledge of RBC geometry both in the normal state and in pathophysiologic conditions such as hereditary spherocytosis (16) cell disease (1) is of considerable basic scientific and clinical interest.…”

“…From measurements of the outer sphere diameter (D), the total length (L), and PID, the membrane area and the cell volume can be exactly calculated (7). The minimum cylindrical diameter (MCD; pm), which is the smallest-diameter pore the cell can completely enter without loss of volume, can then be calculated from the area and volume (2,7).…”

Molecular sieving action of the cell membrane during gradual osmotic hemolysis

“…Both the surface-area and volume distributions of a human's RBC's in isotonic solution are remarkably Gaussian and appear to represent -64-single population distributions (Canham and Burton, 1968;Canham and Parkinson, 1970;Evans and Fung, 1972;Groom and Anderson, 1972;Jay, 1975). In isotonic solution, RBC's often present a bimodal (Lushbaugh, Bassman and Glascock, 1962) or broad nonGaussian (Weed and Bowdler, 1967) Coulter frequency distribution.…”