Effects of Sperm Counts on In Vitro Fertilization and Early Embryonic Development of Mice

【Objective】The effects of different sperm counts on in vitro fertilization and early embryonic development of mice were studied, and the assisted reproductive technique of mice was further improved by comparative analysis. 【Methods】In the test, sperms obtained from the epididymal tail of 9 weeks old C57BL/6 male mice were randomly selected and put into HTF culture medium, which cultured in carbon dioxide incubator for 1 hour. The sperm counts of semen solution of 1, 3, 5, 10, 15 and 20 μL were calculated, the corresponding semen solution absorbed into the oocyte clusters which obtained after the superovulation of 4 weeks old C57BL/6 female mice, and the in vitro fertilization rate and the development rate of 2-cell embryos calculated after in vitro culture for 24 hours.【Results】Sperm counts of 1, 3, 5, 10, 15 and 20 μL semen solution were 0.25 (±0.23)×106, 1.23 (±0.31)×106, 2.03 (±0.35)×106, 3.95 (±0.33)×106, 6.50 (±0.76)×106, and 9.88 (±0.52)×106 (units/mL). At the same time, the in vitro fertilization rates of mice were 88.92%, 95.17%, 94.29%, 90.56%, 85.89% and 78.26%, respectively, and the development rates of 2-cell embryos were 78.21%, 81.75%, 81.51%,77.42%, 70.47% and 50.76%, respectively. The in vitro fertilization rates and the 2-cell embryo development rates with sperm counts of 1.23 (±0.31) ×106 and 2.03 (±0.35)×106 (units/mL) were better than those of others, with no significant difference,but were extremely significantly higher than those with sperm counts of 6.50 (±0.76)×106, 9.88 (±0.52)×106 (units/ mL).【Conclusions】Various sperm counts have significantly different effects on the in vitro fertilization and early embryonic development of mice. The appropriate sperm numbers were 1.23 (±0.31)×106-2.03 (±0.35)×106 (units/mL) , which can effectively improve the in vitro fertilization rates of mice and promote the normal development of embryos.