Table 1 Effect of HCO₃⁻ concentration on in vitro sperm fertility. A) Monophasic IVF: performed in TALP medium containing different HCO₃⁻ concentrations (0 mmol/L, 5 mmol/L, 15 mmol/L and 25 mmol/L) for 18 h of co-culture at 38.5 °C. B) Biphasic IVF (Sperm pre-incubation + Monophasic IVF): sperm were pre-incubated in TALP for 60 min in 5 mmol/L, 15 mmol/L or 25 mmol/L and then IVF was performed in TALP medium with the same or higher HCO₃⁻ concentration for 18 h of co-culture at 38.5 °C

n

Pen, %

Mon, %

SPZ/O

SPZ/ZP

Efficiency, %

216

0^a

–

–

0.3 ± 0.1^a

0^a

204

21.6 ± 2.9^b

61.4 ± 7.4^a

1.7 ± 0.2^a

2.8 ± 0.2^b

13.2 ± 2.4^b

206

79.6 ± 2.8^c

32.9 ± 3.7^b

4.0 ± 0.3^b

4.9 ± 0.5^c

26.2 ± 3.1^c

280

97.5 ± 0.1^d

8.8 ± 1.7^c

6.6 ± 0.3^c

8.8 ± 0.5^d

8.6 ± 1.7^b

n

Pen, %

Mon, %

SPZ/O

SPZ/ZP

Efficiency, %

Sperm pre-incubation

IVF

5

15

171

46.8 ± 3.8^a

36.2 ± 5.4^ab

3.0 ± 0.2^ab

3.4 ± 0.2^a

17.0 ± 2.9^a

5

25

172

54.1 ± 3.8^a

21.5 ± 4.3^a

4.4 ± 0.3^c

4.1 ± 0.3^abc

11.6 ± 2.4^a

15

15

165

69.7 ± 3.6^b

48.7 ± 4.7^b

2.4 ± 0.2^b

3.6 ± 0.2^ab

33.9 ± 3.7^b

15

25

164

76.8 ± 3.3^bc

25.4 ± 3.9^a

3.6 ± 0.2^ac

4.5 ± 0.2^bc

19.5 ± 3.1^a

25

25

171

86.6 ± 2.6^c

24.3 ± 3.5^a

3.4 ± 0.2^a

4.8 ± 0.3^c

21.0 ± 3.1^a