1. Sperm are produced by the testes and are mainly stored in the epididymis and expelled from the body during ejaculation. Current research suggests that the testes can produce between 40 million and 100 million sperm per day. (As shown below, sperm are produced by the varicocele.) 2. Normal sperm have a head and a tail. The head (sperm nucleus) contains the genetic information of the father, and there is a cap-like structure at the top of the head called the acrosome, which contains substances necessary to cross the egg cell, and this substance is medically called acrosomal enzyme. The long tail of the spermatozoon is like the tail of a tadpole, and the tail helps the sperm move when it swings. None of these structures of the sperm should be missing. 3. To fertilize an egg cell, the sperm must travel a long distance to encounter the egg cell, which requires the sperm to have normal motility, so a normal tail structure is indispensable. At the same time, the sperm must also have the ability to penetrate the outer membrane of the egg cell, that is, it needs to have a weapon to penetrate the egg cell, the acrosome, so that the sperm can enter the egg cell. In other words, a sperm with a complete and normal structure is the basis for its ability to move and penetrate. (As shown above) 4. Normally, the oocyte accepts only one normal sperm to penetrate its outer membrane and become a fertilized egg. 5. If the sperm structure is abnormal (semen tests show a high rate of malformation), the sperm motility and penetration ability will be affected and these sperm will either not be able to move to the location of the egg cell or not have the ability to penetrate the outer membrane of the egg cell, therefore both are unable to fertilize the egg cell, which is a common cause of male infertility. （This is a common cause of male infertility. (Below, a diagram of various abnormal sperm morphologies) 6. In recent years, the Israeli biologist Oren Hasson has made a new study on male infertility. The current theories do not yet provide an adequate explanation for male infertility. In some infertile men, there are super sperm, which are so motile and penetrating that they often cause “multiple sperm to penetrate the egg cell”, making it difficult for the egg to be fertilized. Of course, this theory needs to be confirmed by further clinical studies. (2 super sperm penetrate the follicular membrane in the picture below)