Defined Combinations of Cryomedia and Thawing Extenders Influence the Viable X-Y Boar Sperm Ratio in Vitro.

BACKGROUND: It is believed that plasma membrane X- and Y-chromosome bearing sperm are different; therefore the freezing and thawing process may affect X- and Y-sperm differently.

OBJECTIVE: The objective of this study was to investigate the effect of cryomedia and thawing extenders on the survival of X and Y-sperm.

MATERIALS AND METHODS: Three different cryomedia and thawing extenders were compared. Viable motile sperm were separated using a swim-up technique. Real-time PCR was used to identify the sperm type.

RESULTS: Using CryoA for freezing and Beltsville-Thawing-Solution (BTS) as the thawing extender yielded significantly higher numbers of viable motile Y sperm (64 percent) than control (48 percent) (P < 0.01). Conversely, semen freezing with CryoC and thawing with Androstar Plus gave a significantly lower number of viable motile Y sperm (32 percent) than control (51 percent).

CONCLUSION: Our results revealed that defined combinations of cryomedia and thawing extenders significantly altered the survival ratio of frozen-thawed X-Y sperm in vitro, which has potential implications for artificial insemination.