Calculation of surface area and volume of human erythrocytes from scanning electron micrographs

This article demonstrates that surface and volume measurements of individual human erythrocytes with varying shapes can be obtained from scanning electron micrographic stereopairs using an approach based on established principles of photogrammetry. Instead of calculating the coordinates of several hundred points plotted for each cell, a procedure that proves tedious and time-consuming, we show that a reasonable approximation of cell surface and volume can be achieved from simple geometrical models constructed with a small number of carefully measured points and angles, using a stereocomparator. The values obtained for two normal erythrocytes and for two distorted red cells from a patient with congenital pyruvate kinase deficiency haemolytic anaemia are consistent with available information on the geometry of these cells. Because scanning electron microscopy requires extensive manipulation of the cells, the values obtained cannot be applied to fresh living material, but appear fairly accurate for the purpose of comparison between cells prepared in the same manner.