Morphological Perinuclear Theca Alterations Are Related to Acrosome Loss in Cryopreserved Boar Spermatozoa

The aim of this study was to determine the effect of cryopreservation of boar spermatozoa on the integrity of the Perinuclear Theca (PT) substructure and the integrity of the acrosome. Semen from 12 boars were divided in two fractions; one was cryopreserved and thawed the other was used fresh as a control sample. In order to expose the PT structure both samples were treated with the nonionic detergent Brij 36-T and processed for electron microscopy observation after negative staining. Before freezing, 16.7% of spermatozoa showed PT-substructure alterations, that increased to 53% after freezing and thawing (p< 0.001). Similarly, acrosome damage increased from 19.5-54.9% after cryopreservation. Furthermore, significant correlations were found between PT-substructure alterations and acrosome defeat. In addition, whilst no difference in PT substructure damage was observed between breeds in control sample, the Mexican hairless breed had significantly more spermatozoa with damage PT substructure after freezing-thawing. The acrosome loss of boar spermatozoa increased with an increased proportion of PT-altered spermatozoa.