A Mo-Flo SX flow cytometer/sperm sorter (Dako
Cytomation Inc., CO, USA) equipped with an argon laser
(wavelength: 351 at 150 mW) was used. Dulbecco’s
phosphate-buffered saline (DPBS) served as the sheath
fluid. The instrument sheath pressure was set to 40 psi,
and the trigger rate was adjusted to 25,000 cells/s. After
collecting 7–8
×
106 sperm per tube, the two populations
were pooled. The samples were centrifuged at 3000
×
g
for 5 min, and the pellets were re-suspended in HEPESbuffered
media.