Effects of extenders and time of storage before freezing on motility and fertilization of cryopreserved muskellunge spermatozoa

The usefulness of five extenders for cryopreservation of muskellunge semen was studied in fertilization trials and computer-assisted semen analysis (C ASA) of postthaw sperm motility. The effect of pre freezing storage time be fore cryopreservation on success of cryopreservation was also analyzed. A 5 0% fertilization rate (compared with fresh semen) of the extender containin g 10% dimethyl sulfoxide (DMSO) in seminal-plasma-mimicking medium (SPMM) s upplemented by 10% egg yolk was significantly higher than in extenders cons isting of 10% DMSO, 0.6 M sucrose, and 10% egg yolk or 20% glycerol and 0.3 M glucose. Spermatozoa cryopreserved with DMSO-SPMM-egg yolk extender had the highest values of straight-line velocity and linearity of movement. Sig nificantly lower fertilizing ability and curvilinear velocity were found fo r semen specimens stored on ice for 5 h before freezing compared with speci mens stored for 1 h. Although spermatozoa cryopreserved with extender conta ining 10% methanol had only traces of motility or no motility at all after thawing, fertilization trials indicated that their fertilizing ability was preserved. Despite a lack of motility after thawing, these spermatozoa coul d have been activated by egg components, thus indicating that they could ha ve been motile during fertilization. This possibility suggests that the mot ility pattern of muskellunge spermatozoa may be influenced during fertiliza tion by egg components.