Abstract
This study investigated the ability of various diluents used in the cryopreservation of fish sperm (extenders) to reversibly suppress the motility of pejerrey Odontesthes bonariensis spermatozoa. A modification of Mounib Solution with 100mM NaHCO3, 125mM sucrose, and 6.5mM reduced glutathione was found to be a satisfactory extender for pejerrey sperm, although variants with higher osmotic pressures may be necessary to minimize motility in some cases. In contrast, other extenders either elicited full activation or irreversibly impaired spermatozoan viability. The effectiveness of Modified Mounib Solution as an extender for pejerrey sperm appeared to be primarily due to the attainment of isosmotic conditions to the seminal fluid through the balance of electrolytes and non-electrolytes, the absence of K+, and the presence of Na+. The presence of bicarbonate, the low concentration of proteins or phospholipids, and a slightly alkaline pH apparently contributed to the effectiveness of this extender.
