Turbidimetric analysis of human sperm motility.

A turbidimetric method has been developed for determining rapidly the fraction of sperm in human ejaculates which show the most vigorous motility. The method is based on the fact that sperm cells so endowed will be the first to swim upward into clear medium from a concentrated cell suspension at the bottom of an optical cuvette. This results in a time-dependent increase in turbidity in the medium which is recorded spectrophotometrically as an increase in absorbance. The determination requires 10 minutes and yields both the fraction of rapidly moving sperm, FRM, and their average velocity, VRM. Examination of 25 samples yielded FRM values of 10% or lower, whereas values for VRM averaged about 100 microns/second. These vigorously motile cells may be the best candidates for fertilization, and samples with a high fraction of such cells should have high fertilizing capacity. It is suggested that this simple turbidimetric test be used in evaluation of human semen as a possible indicator of fertilizing capacity.