“…Current techniques for separation of X from Y‐bearing sperm are based on swimming patterns, differing mass and motility, DNA content, size and weight, electrical surface charge, centrifugal countercurrent distribution, volumetric differences and immunologically relevant properties (Ericsson et al., 1973; Jain et al., 2011; Prasad et al., 2010). Previous studies using fluorescence in situ hybridization (FISH) approach indicated that albumin gradient (Flaherty & Matthews, 1996; Wang et al., 1994), sephadex column (Vidal et al., 1993) and swim‐up techniques (Han et al., 1993; Lucio et al., 2009) did not significantly separate X‐ and Y‐bearing sperm in human, while the discontinuous percoll gradient shows a higher efficiency (Pryor et al., 2004; Wang et al., 1994).…”