New aspects of sperm-zona pellucida binding

Sperm-zona pellucida binding tests have become a widely used diagnostic application for clinicians to obtain guidance in so far as the therapeutic approach of the subfertile couple is concerned. Expanding the oocyte sources is imperative to ensure the consistent use of sperm-zona binding assays. Sources include oocytes derived from post-mortem ovaries, inseminated non-fertilized IVF oocytes and recycled hemizonae. Identification of specific gamete dysfunction is one of the most formidable tasks and fertilization disorders due to defective sperm-zona pellucida interaction are relatively common in the clinical practice, thereby emphasizing the importance of sperm-zona binding tests as diagnostic/predictive tests. Independent publications from Norfolk (USA), Melbourne (Australia), Tygerberg (South Africa) and Israel of highly comparable results confirm that sperm-zona binding tests are good predictors of fertilization. Studies using solubilized human pellucida recently evaluated the influence of solubilized human pellucida on spermatozoa during the capacitational process and subsequent sperm-zona binding. Involvement of G protein and carbohydrate moieties in sperm-zona pellucida binding emphasized the biological and biochemical properties of lectin and have afforded much weight to their employment as membrane probes to evaluate cell surface components. Attention has been focused on the alterations of sperm surface receptors (oligosaccharides) during the differential pathway, epididymal transit and capacitation.