Urinary bladder, ionic composition of seminal fluid and urine with characterization of sperm motility in tench (Tinca tinca L.)

Summary A small urinary bladder attached to the seminal duct in caudal part of the abdominal cavity was registered for the first time in dissected males of tench. The urinary bladder wall was of whitish color and the bladder contained 0.5–2 ml of urine. When collected in the experiment, the tench sperm was white-colored. Spermatozoa density is highly variable due to contamination by urine, and the latter additionally activates spontaneous motility of the spermatozoa. Seminal fluid contains ions such as Na+ (18.4 ± 1.3 mm), K+ (1.9 ± 0.6 mm), Ca2+ (0.6 ± 0.2 mm) and Mg2+ (0.5 ± 0.1 mm), leading to osmolality of 230 ± 82 mOsmol kg−1 depending on the dilution by urine. Urea was detected in urine samples uncontaminated by sperm with an osmolality of 85 ± 58 mOsmol kg−1. Urine also contained high concentrations of ions such as Na+ (30.9 ± 8.9 mm), K+ (4.3 ± 2.9 mm), Ca2+ (0.9 ± 0.5 mm) and Mg2+ (0.6 ± 0.2 mm). The spontaneous sperm activation by urine was up to 100%, but could be prevented by collection in an immobilizing solution. Motility was observed for 90–100% spermatozoa just after their transfer to distilled water or in a swimming medium (SM, 30–45 mm KCl) with a velocity of 120–140 μm s−1. A flagellar beat frequency of 60–70 Hz and forward motility lasted up to 80 s in distilled water, and up to 180 s in SM at room temperature.