The spermatozoon of the African catfish: fine structure, motility, viability and its behaviour in seminal vesicle secretion
The spermatozoon of the African catfish Clarias gariepinus is a simple organized aquasperm although it reveals very unique characteristics: the cytoplasmic channel is lacking, the mitochondria form a complex structure and the arrangement of the centriolar complex is species specific. Semen has high initial motility rates (c. 70–90%) and swimming velocities (c. 120–140 μm s−1), the main swimming type is linear. Motility duration in water is 30 s and is prolonged only to 40 s in NaCl solutions or more complex bu ered motility activating saline solutions. A pH between 7.0 and 9.0 has no e ect on the sperm motility parameters. Motility is completely and reversibly suppressed in electrolyte and non‐electrolyte solutions with an osmolality of 200 mosmol kg−1. During immotile storage the sperm viability is influenced by the osmolality and the potassium levels of the storage medium, by the temperature and by the dilution. At optimal conditions (bu ered sperm motility inhibiting saline solution: 150 mmol l−1 NaCl, 2.5 mmol l−1 KCl, 1 mmol l−1 CaCl2, 1 mmol l−1 MgSO4, 20 mmol l−1 Tris solution, pH 8.5; dilution rate 1: 5; storage temperature, 4°C) sperm viability persists for >7 days. High viscosity of the pure seminal vesicle secretion completely inhibits the sperm motility. When the seminal vesicle secretion is diluted in water the viscosity decreases and the motility suppressing e ect is neutralized. When semen is mixed with seminal vesicle secretion the sperm viability decreases to zero within 10 min.
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Document Type: Research Article
Affiliations: Institute for Zoology, Hellbrunnerstrasse 34, 5020 Salzburg, Austria
Publication date: 2002-03-01