Separation of bovine X and Y sperm based on surface differences

Abstract Aqueous two‐phase partition involving thin‐layer counter current distribution (TLCCD) has been used to assess surface heterogeneity of ejaculated bovine sperm. When partitioned in charge‐insensitive aqueous two‐phase systems, which detect non‐charge associated surface properties, the sperm fractionates into two distinct populations. Using a Y‐chromosome‐specific DNA marker, it has been shown that one of these populations is enriched in Y chromosome bearing sperm. However, this population is not pure—it consists of 80% Y sperm, with the other 20% being X sperm. All the sperm in the original population that had begun to undergo the acrosome reaction were separated into this same peak; the sex chromosome composition of these sperm is unknown. Since the aqueous partition of sperm is based on surface properties these results suggest that two populations of Y sperm exist that have different surface characteristics. © 1993 Wiley‐Liss, Inc.