Evaluación de dos protocolos de congelación de espermatozoides epididimarios en la especie Canis Lupus familiaris

Abstract

This study was aimed to assess two canine epididymal sperm freezing protocols on cryosurvival, one conventional (CF) that uses static liquid nitrogen (LN2) vapors, and another ultra-rapid (UF) that directly plunges drops (30uL) of sperm in LN2. For this purpose, sixty epididymides from 30 orchiectomized adult dogs were used. The sperm samples were retrieved by retrograde flushing and then thirty pools were conformed (3 epididymal samples/pool). Each pool was divided into 2 aliquots that were cryopreserved with both CF and UF protocols using either 5% glycerol and 250 mM sucrose, respectively, added to the TCG-EY extender (tris, citric acid, glucose plus 20% egg yolk). The results showed that the UF protocol produced lower motility (total and progressive) and acrosomal membrane integrity (P < 0.05) than the CF protocol. However, the kinetic variables (curvilinear and rectilinear velocities, straightness, linearity, oscillation, the amplitude of lateral head displacement and beat-cross frequency) and plasma membrane integrity (viability) did not differ (P > 0.05) between both cryopreserving protocols. Efficiently, the UF protocol did not vary (P > 0.05) the length, width, area, and perimeter of the sperm head with respect to the non-frozen values. In conclusion, the UF protocol affects motility compared to the CF protocol. Despite this, the achievement of kinetics and viability levels in conjunction with the invariance of the morphometric head dimensions opens up good expectations for its use in the efficient cryopreservation of epididymal sperm from domestic and non-domestic canines.