An improved method of sperm selection by glass wool filtration.

An improved method of sperm selection by glass wool filtration is introduced. After incubation of glass wool filtrates for 30 min at 37 degrees C in a conical-shaped 1.5-ml tube, an enrichment of highly motile spermatozoa was found in the bottom layer of the tube. The effect turned out to be dependent on the conical shape of the tube, as it was not observed in flat-bottomed tubes. Native ejaculates (obtained from 30 men) and their glass wool filtrates were analysed by cell counter, computer-assisted sperm-motility analysis, morphological differentiation and supravital staining of spermatozoa. When 400 microl of ejaculate, diluted with 800 microl of medium, was applied to the top of a column consisting of a 1-ml disposable syringe barrel gently packed with 15 mg of glass wool to a depth of 6 mm, an enrichment of viable spermatozoa was found in the first three 100-microl fractions taken from the bottom of the tube. It is the simplicity of this technique that makes it so easily applicable.