Annexin

Innovative methods to select sperm subpopulations with the best fertilizing ability are needed in assisted reproductive techniques (ART) in order to improve fertilization and pregnancy rates, while also considering possible epigenetic effects on the offspring. Molecular based selection methods are searched for, under the premise that they could be an improvement over classical selection by morphology and movement. One of these methods sustains the elimination of sperm that can bind to annexin A5 (ANX V), coupled to paramagnetic beads, through the phosphatidyl-serine exposed on their membranes upon apoptosis. Although reports accumulate about the use of this method, controversy persists as to the benefits of ANX V based sperm selection in ART. In this review we consider the arguments in favour and against this method and conclude that to the moment the evidence does not support MACS regular use in ART.