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MONTHLY VARIATION IN SPERM MOTILITY IN COMMON CARP ASSESSED USING COMPUTER-ASSISTED SPERM ANALYSIS (CASA)
Jackson, S., G. Toth, H. W. McCarthy, J. Torsella, AND M. Smith. MONTHLY VARIATION IN SPERM MOTILITY IN COMMON CARP ASSESSED USING COMPUTER-ASSISTED SPERM ANALYSIS (CASA). Journal of Fish Biology 48(6):1210-1222, (1996).
Sperm motility variables from the milt of the common carp Cyprinus carpio were assessed using a computer-assisted sperm analysis (CASA) system across several months (March-August 1992) known to encompass the natural spawning period. Two-year-old pond-raised males obtained each month were primed with an exogeneous hormone injection of carp pituitary extract and stripped of milt 18-24 h later. The milt was diluted, activated and videotaped using a high-speed (200 Hz) videocamera and recorder. Videotaped samples were subsequently analysed using the CellTrak/S CASA system (Motion Analysis Corp.) for percent motility, curvilinear and straight-line velocity. In addition to assessing changes in motility parameters across several months, a comparison was made between two predilution/activation media combinations (homologous seminal plasma/NaC1+HEPES v.2-h incubation in 200 mm KC1+Tris/Tris). The percentage of motile cells assessed immediately after activation was significantly greater in the summer months (May,June,July) when compared to a spring sampling point (March); when assessed 1 min after activation, cells prediluted in seminal plasma maintained a higher percentage of motility than those prediluted in KC1. Curvilinear and straight-line velocities exhibited a slight seasonal trend; variations in response to the predilution treatments were observed with these measurements. Sperm count gradually increased through April and May (9.63x10 9 to 2.38x10 10ml-1 milt), declined in June and July (to 1.83x10 10 ml-1 milt), and was followed by a steep increase in August (2.74x10 10 ml-1 milt). Mean seminal plasma osmolality remained relaively constant (250-265 mOsmol kg-1) throughout the sampling period.