Volume and shape of normal human spermatozoa

An improved apparatus for measuring the electrical size of particles, developed in this laboratory and based on the principle of the Coulter counter, is used to size human spermatozoa. The typical size distribution is unimodel, with a skew to the right. The actual quantity determined by the measuring system is electrical size (i.e., shape factor x volume); in order to extract the volume, it is necessary to obtain an independent measure of particle shape. This is done by estimating the relative contributions of each part of the spermatozoon, and gives a weighted value for the shape factor of 1.28. The mean volume of spermatozoa from 25 normal human seminal fluid specimens is found to be 17.4 ± 1.46 cu μm and the modal volume, 15.2 ± 1.27 cu μm. These values are compared with data reported in the literature after correcting the latter for the effects of particle shape.