Unraveling the intricacies of mammalian fertilization

It is imperative to understand the molecular basis of various steps involved during fertilization. In the manuscript by Bianchi et al.1 a novel protein, Juno on egg membrane (oolemma) has been characterized that binds to sperm specific protein, Izumo-1. Monoclonal antibodies against Juno inhibited in vitro fertilization. Juno knock-out female mice failed to deliver litters on mating. It is rapidly shed from oolemma after fertilization, suggesting its role in preventing polyspermy. Taken together these studies will help in our understanding of sperm-egg recognition mechanisms and also facilitate development of new fertility treatment regimens and novel contraceptives.