part of has part membrane fusion involved in acrosome reaction single fertilization acrosome reaction Wikipedia:Acrosome_reaction GO:0007340 If the release of the acrosome content occurs before the sperm reaches the zona pellucida, consider using premature acrosome loss. The discharge, by sperm, of a single, anterior secretory granule following the sperm's attachment to the zona pellucida of the oocyte. The process begins with the fusion of the outer acrosomal membrane with the sperm plasma membrane and ends with the exocytosis of the acrosomal contents into the zona pellucida. biological_process Reactome:R-HSA-1300645 reproductive process acrosomal vesicle exocytosis