Abstract
Ejaculated canine spermatozoa were incubated at a concentration of 0.6-4.0×108/ml, using a modified Krebs-Ringer bicarbonate solution (TYH) at 37C under 5% CO2 in air. Motility, aggregation, viability, hyperactivated movement and acrosome reaction of spermatozoa were examined at 0, 1, 2, 3, 4, 5 and 6 h of incubation. Motility and viability decreased slightly and aggregation increased at 1h of incubation, then did not significantly change until 6h of incubation (about 3.4, 65% and 75%, respectively). The percentage of spermatozoa showed hyperactivated movement and acrosome reaction increased remarkably at 3 h (53.9%) and 4h (68.0%) of incubation, respectively. The 4 h-incubated spermatozoa were inseminated at a concentration of 0.5 or 1.0×106/ml to the oocytes incubated in TYH (bovine serum albumin (BSA) -) with 10% fetal bovine serum for 48 h or 72 h. The spermatozoa penetrated into the zona pellucida at 1h after insemination. At 2 h after insemination, the spermatozoa penetrated into the cytoplasm (34.0%), then the percentage increased significantly to 63.4% at 4h after insemination. These results suggest that ejaculated canine spermatozoa are capacitated by 4h incubation in TYH.
