Human sperm--egg interactions and their disorders: implications in the management of infertility

The present era of infertility management is characterized by an increasing interest in defects of sperm--egg interactions. When the spermatozoon meets the egg, it must first react with the enveloping coat which controls sperm access to the cell surface of the oocyte. Adequate sperm motility is a major condition for penetration through the egg investments. The ability of spermatozoa to respond to physiological stimuli by a timely acrosome reaction is another necessary prerequisite for this event, as well as for sperm fusion with the oocyte. The clinical significance of current laboratory tests evaluating different aspects of gamete function is discussed and a practical guide is given for their indication and interpretation and for the use of their results in choosing rational therapy.