Motility assay of human sperm by photon correlation spectroscopy.

Microscopic methods of performing motility assays of spermatozoa are slow, subjective, and involve a small number of spermatozoa. Laser light-scattering methods can analyze the motility of many spermatozoa within minutes. The swimming speed distribution of human spermatozoa was investigated by photon correlation spectroscopy. The sperm was diluted in seminal plasma to avoid modifying the viscosity. The swimming speed distribution was reconstructed from the correlation data by Stock's method of splines. When compared with a videomicroscopic assay, the reconstructed swimming speed distribution accurately reflects translational motion between 0 and 80 micrometers per second, while for speeds greater than 80 micrometers per second the distribution is distorted by the effects of rotational motion.