It is well-known that controversies and questions exist in all fields of knowledge.Beyond doubt,they play an important role in driving the development of science and technology.It is,therefore,not surprising that controversies also arise in the area of reproductive biology,and it is our belief that thorough testing of alternative hypotheses will accelerate our understanding of this field.One of the open questions in reproduction is how the sperm activate the egg during fertilization.Over the years,different mechanisms have been proposed,which led to multiple discussions.