DISCONTINUOUS PERCOLL GRADIENTS ENRICH X-BEARING HUMAN SPERMATOZOA - A STUDY USING DOUBLE-LABEL FLUORESCENCE IN-SITU HYBRIDIZATION

The aim of this study was to evaluate the efficacy of enriching X-bear ing human spermatozoa using 12-step (25-80%) discontinuous Percoll gra dients. X- and Y-bearing spermatozoa were simultaneously identified in neat semen (controls) and in 80% Percoll fractions from the same samp les using double-label fluorescence in-situ hybridization and chromoso me-specific DNA probes. Hybridization and labelling efficiencies of 95 -99% were obtained in all samples. The mean ratio of X- to Y-bearing s permatozoa in the controls was 49,0:48.2, whereas there was a signific ant enrichment (P < 0.0001) of X-bearing spermatozoa in the Percoll fr actions (mean X:Y ratio was 55.1:41.1 or 1.35). The ratio varied from 1.1-1.5 in individual Percoll samples. There were no significant diffe rences in the proportions of aneuploid spermatozoa (XX, YY, XY) betwee n the control and Percoll fractions. We conclude that 12-step disconti nuous Percoll gradients enrich X-bearing spermatozoa, but the degree o f enrichment is insufficient for use in preconceptional sex selection.