Effects of different Zinc levels in the sperm culture medium on sperm recovery and quality of sperms in the swim up procedure for sperm processing

A controlled in vitro study was carried out to observe the effect of different Zinc (Zn) levels on sperm recovery rate, chromosome integrity, cell membrane integrity and motility in the swim up procedure. Semen samples were obtained from males who underwent seminal fluid analysis at the Infertility Laboratory, Department of Obstetrics and Gynaecology, Faculty of Medicine, Ragama. Twenty normozoospermic samples were randomly selected for the study and each sample was processed with supplemented Earl's Balanced Salt Solution (EBSS) containing different concentrations of Zn [0.5ml of supplemented EBSS with 25μlitres of solution containing 0.6μmol (group 1) and 1.2 μmol (group 2) of Zn respectively]. One aliquot processed with 25 μlitres of physiological saline with added EBSS served as the control. Pre and post wash sperm counts and motility were recorded immediately after processing. Post wash sperms from the three groups were observed for chromosome integrity, cell membrane integrity, and motility. Motility changes after four hours of incubation were also observed. The mean sperm concentration showed an increase in group 1 compared to the control sample [21.87 ± 21.61 (SD) millions / ml compared to 18.34 ± 19.73 millions / ml, P < 0.05] whereas a reduction was observed in group 2 [16.25 ± 17.73 (SD) millions/ ml compared to 18.34 ± 19.73 millions / ml, P > 0.05]. The mean differences in sperm concentration compared to the control showed statistically significant differences in both groups where an increase was observed in group 1 [3.52 ± 4.96 (SD) millions / ml] and a reduction in group 2 (- 2.08 ± 6.59 millions/ ml). The mean differences in sperm recovery rate showed significant differences in group 1 [8.97 ± 14.04 (SD) millions/ml] and group 2(-4.85 ± 17.92 millions/ml) compared to the control. It was an increase in group 1 and a reduction in the sperm recovery rate in group 2. A significant reduction in mean sperm motility was observed in group 2 [67.33% ± 18.52 (SD) vs. 91.00% ± 9.60, P < 0.05] after four hours of incubation. Though a reduction was observed in group 1 it was not statistically significant (83 .33% ± 8.72 vs. 93.60% ± 5.01, P > 0.05). The motility reduction was significantly greater in group 2 compared to group 1 (26.01% ± 20.24 vs. 10.97% ± 8.35, P < 0.05). Chromosome integrity and cell membrane integrity of sperms were not affected by different Zn levels. In conclusion, low levels of Zn in the sperm processing medium (EBSS) have a beneficial effect on sperm recovery in the swim up procedure. Key words: Zn added EBSS, Harvesting rate,