Abstract

To asses the marital infertility causes, it is estimated that male factor is responsible in at least the 50% of the cases. The functional competence of sperm appears to be directly related to the morphology of the gametes. Particularly the normal structure of the sperm's neck components seems to be crucial for successful fertilization and embryogenesis. In the past few years, the use of different techniques of assisted reproduction as a treatment for male infertility has increased. In these techniques, alterations in the neck components could determine the failure of therapy. In spite of this, the subcellular details of sperm necks have been poorly studied. The aim of this study was to analyze comparatively the ultrastructural characteristics of the sperm's necks in fertile and infertile men. The sperm obtained from semen samples was analyzed by photonic and transmission electron microscopy (TEM). The study of the sperm sections revealed different alterations of the neck (total disruption of components, reduced implantation zone, misalignment, headless necks, proximal centriole and dense columns altered) both in patients and in controls. These changes were observed more frequently in infertile men. Neither of the described malformations was observed in a unique and repetitive way. Studies by TEM could guide the choice of specific techniques for the diagnosis of infertility, contributing to the selection of more appropriate assisted reproduction treatment.