Annexin-V magnetic-activated cell sorting (MACS) is a new tool to optimize sperm selection in assisted reproduction. The technique is based on the binding of superparamagnetic Annexin-microbeads to externalized phosphatidylserine at the outer leaflet of the plasma membrane of sperm with activated apoptosis signaling or membrane damage. The combination of Annexin-V MACS and density gradient centrifugation was demonstrated to enhance clinical pregnancy rates in ICSI cycles. This chapter focuses on the practical details of Annexin-V MACS.
