Effect of porcine sperm-treatment and sperm-zona pellucida (ZP) co-incubation period on the rate of Y chromosome-bearing sperm bound to ZP
2008
Shiono, H.(Tokyo Univ. of Agriculture (Japan)) | Iwata, H. | Saito, K. | Urakawa, M. | Kurita, A. | Kon. Y. | Sasaki, Y. | Kuwayama, T. | Monji, Y.
In the present study, frozen-thawed (FT) or fresh (F) porcine sperm were co-incubated with zona-pellucida (ZP) for 5 or 300 min. In some experiments, the sperm were pre-incubated for 2 h or cooled to 4degC prior to co-incubation with ZP for 5 min. The rate of Y chromosome-bearing sperm (Y-sperm rate) bound to the ZP was analyzed by in situ hybridization. The Y-sperm rate of FT and F sperm was 49.8% and 51.0%, respectively, which was not different from the theoretical rate (50%). When FT and F sperm were co-incubated with ZP for 5 min, the Y-sperm rate was significantly greater than the theoretical rate (FT 59.0%; F 55.1%). Increasing the ZP-FT sperm co-incubation period from 5 min to 300 min decreased the Y-sperm rate toward the theoretical rate (from 59.0% to 49.7%). Increasing the ZP-F sperm co-incubation period, however, did not affect the Y-sperm rate (5 min, 55.1%; 300 min; 55.7%). Cooling the F sperm to 4degC also did not affect this skewed Y-sperm rate. Pre-incubation of FT and F sperm, however, restored the skewed Y-sperm rate toward the theoretical rate (53.5%; F 52.3%). Thus, Y chromosome-bearing sperm have a greater tendency to bind to ZP. This tendency was attenuated, however, when the ZP-FT co-incubation period was extended or when FT and F sperm were pre-incubated.
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