Functional activity of epididymal Chinchilla laniger spermatozoa cryopreserved in different extenders

Chinchilla laniger is an endangered species and improved cryopreservation of spermatozoa would constitute a significant advance in the development of assisted reproductive techniques in this species. The functional activity of epididymal spermatozoa from adult males was studied immediately after extrusion and after 24 hours incubation, and the ability of five extenders to protect these gametes during cryopreservation was determined. A decrease in sperm motility, viability, acrosome intact cells and response to hypo-osmotic swelling test was detected 24 hours later. The extenders here assayed showed well-defined differences in their cryoprotective ability; however such differences could not be attributed to any one of their individual components. The presence of TES plus Tris, the proportion of the individual constituents and/or the differences in metabolic substrate content could explain the above-mentioned finding. The results indicate that cryo-buffer II (TES-Tris-egg yolk-fructose-glycerol) is the most powerful protector of sperm functional activity in this species.