ABSTRACT
The introduction of the intracytoplasmic sperm injection (ICSI) technique in assisted conception has substantially reduced the quality threshold of semen in terms of concentration, motility, and morphology of spermatozoa that are necessary for a patient to be treated. Human sperm vacuoles were first described as 'nuclear holes' when examined by electron microscopy and two-dimensional (2D) imaging. An microscopic approach aimed at selecting the best sperm is based on the application of polarization light microscopy. Some studies have analyzed the status of sperm DNA integrity in relation to the patterns of birefringence. In general, the traditional polarized light microscope differs from a standard transilluminating microscope in that it includes a polarizer and a compensator before the condenser and an analyzer behind the objective lens. The relationship between the pattern of birefringence and the acrosome status was based on transmission electron microscopy (TEM) results for which it was proposed that partial birefringence was due to an already occurred acrosome reaction.
