Enrichment of human X- and Y-chromosome bearing spermatozoa by density gradient centrifugation.

Human spermatozoa (120--180 Mill/0.6 ml Tyrode solution) were laid on the top of a continous density gradient column consisting of 4--16% bovine serum albumin. The columns were then centifuged at 1500--1600 rpm (200-240 g) at 20 degrees C or 4 degrees C for 15 min. By this procedure the spermatozoa sedimented within the tubes of normal distribution curves. The mean percentages of y-spermatozoa gradually decreased from 62,3 +/- 6,1% (max. 70%) in the upper fractions to 42,4 +/- 3,8% (min. 37%) in the bottom fractions. These results could be verified by inseminations of rabbit does with spermatozoa separated by the same technique.