Effects of sperm concentrations and culture media on fertilization and development of in vitro matured pig oocytes.

This study was carried out to investigate the effects of sperm concentrations and culture media on fertilization and development of in vitro matured pig oocytes. The concentrations of frozen-thawed sperm were 0.2 x 10(7), 2 x 10(7), 20 x 10(7) and 200 x 10(7)/ml, respectively. Culture media were NCSU-23, HEPES-buffered (25 mM) NCSU-23, PZM-3 and PZM-4, respectively. Increasing the sperm concentration from 0.2 x 10(7) to 2 x 10(7)/ml, significantly increased the penetration rate. Also, increasing the sperm concentration from 20 x 10(7) to 200 x 10(7)/ml increased the penetration rate from 62.1% to 69.9%, respectively, with no differences between these two concentrations. A similar pattern was observed for polyspermic penetration and male pronucleus formation. The mean number of sperm per oocyte significantly increased in the 20 x 10(7)/ml and again in the 200 x 10(7)/ml sperm concentrations. The percentage of blastocysts from cleaved oocytes at the 2 x 10(7)/ml sperm concentration was significantly higher than that at the 0.2 x 10(7), 20 x 10(7) and 200 x 10(7)/ml sperm concentrations. The percentage of blastocysts from cleaved oocytes and the cell numbers per blastocyst were significantly higher in the HEPES-buffered NCSU-23 culture medium than in the NCSU-23, PZM-3 and PZM-4 culture media under a gas atmosphere of 5% CO2 in air.