RESEARCHES REGARDING THE ULTRASTRUCTURAL MODIFICATIONS OF SPERMS CELLS BEFORE AND AFTER FREEZING IN DIFFERENT MEDIA

Sperm cryopreservation is a method of ex situ preservation of gametes in all domestic animals, which is extensively used in artificial insemination. There are numerous factors on which the success of freezing sperm and of obtaining living products depends. The composition of seminal plasma, extenders used for dilution, cryoprotective concentrations, reactive oxygen species, and also the cooling rate, influence the quality of sperm cells frozen and thawed and of the number of viable products obtained after the insemination of the cryopreserved sperm. The research of recent years confirms that in sheep and goat, fertility outcome is still very variable, regardless of the conditions and media used for freezing-thawing. Researches show that, regardless of the solvent used, the motility and membrane integrity of sperm deteriorates during cooling and storage at low temperature. These degenerative changes may be the result of lipid peroxidation and excessive production of reactive oxygen species (ROS).Our study presents the results of changes in the integrity of sperm cells membranes of Saanen goats after freezing-thawing, after diluting the buck semen with Tris base extender enriched with 10mm L-cysteine (Sigma), 5 mg/ml BSA (Sigma) and 1mM vitamin E (DL-a-Tocopherol, Merck). After thawing, the highest motility was obtained in the vitamin E and cysteine versions (between 51-55%). Goat semen samples diluted with the 3 antioxidants were processed for examination and analyzed in terms of electron microscopic cellular integrity at all levels (head, midpiece, principal piece and end piece). Electron photography analysis (X10.000) shows that full membranes were observed in a proportion of 49% of cells diluted with Tris-vitamin E at all levels of the cell and at a rate of 37% in sperm cells diluted with Tris-cysteine. Swollen but continuous membranes were considered to be normal. The cell sperm diluted with medium supplemented with BSA displays protein deposits with acicular aspect and membrane with small and frequent gaps. Future researches are targeted at in vivo testing of goat sperm cryopreserved with different antioxidants to determine its fecundity