An improved assay for measuring the antimotility activity of chemical agents towards spermatozoa.

An assay which allows relatively precise determination of the minimum concentration of test compound required to completely immobilize sperm is described. The use of rectangular cross-section capillaries to contain diluted semen allows facile direct comparison of many individual systems under well-controlled conditions. As a result, simultaneous determination of activity in both saline and serum media is feasible. Using this assay, abrupt loss of motility is observed between adjacent cepillaries differing in test compound concentration by as small a factor as 2 1/3 (1.260).