Banca de DEFESA: RÓGENES FERREIRA CAETANO

Vitrification of ovine epididymal sperm

semen, cryopreservation, vitrification, sheep

Sperm cryopreservation allows storage and further use of semen samples. Whereas classic or slow cryopreservation has the limitations of generating ice crystals, demanding expensive equipment, and a longer time for execution, vitrification is an ultra-rapid freezing technique, demanding cheaper equipment and faster execution. The goal of the present work was to write a review about sperm cryopreservation and some technical-related aspects, as well as to study the effects of sucrose addition and higher temperature in the rewarming media on the efficacy of ram epididymal sperm vitrification. Epididymal sperm from 24 rams diluted into five commercial extenders (Blue, B; Red, R; Green, G; Orange, O; e Violet, V), with a final concentration of 200 x 106 sperm/mL were used. The samples were refrigerated at 5 oC, and then vitrified. In the first experiment, the samples were rewarmed by plunging in the same vitrification medium added with different sucrose concentrations (0, 100, 200,400 mM), kept at 37oC. In the second experiment, the samples that presented motile sperm in the first experiment were plunged in the same extenders used in the first experiment, but kept at 70 oC, followed by immediate transfer to a water bath at 37oC. Using different sucrose concentrations or higher temperature during rewarming didn’t result in better sperm protection after rewarming. It was concluded that the challenges to obtaining higher sperm quality-viability after vitrification are unceasing, being apparently ineffective adding sucrose only during rewarming, associated or not with a higher rewarming temperature to 70 oC, when epidydimal ram sperm are vitrified on commercial horse semen extenders, which demonstrate the need for new research in the field of sperm cryopreservation.