- Fertility potential of semen depends upon the presence of viable and motile spermatozoa. A variety of techniques has been reported whereby motile spermatozoa are separated from semen for use in homologous insemination. Using a column of glass beads, we tested various sizes for spermatozoa-separating efficiency. This procedure is quick and simple and results in a significantly better recovery of motile and viable spermatozoa from poor-quality semen. Therefore it has the potential for use in intrauterine insemination for treating male factor infertility.