Fertilization is a union of male and female gametes. fertilization process is very much advanced.The semen of male consists of combination of spermatozoa and accessory fluids. When sperms are deposited in vagina, the sperms starts travel through the uterus upto oviducts. The sperm fuses with the egg at oviduct. Before fusion of sperm with the egg , the egg membrane must be brake , the chemical released by the spermatozoa will collapse the egg membrane . a healthy human ejaculate 4 ml of semen which have 80 to 100 million sperms . out of these only one of the sperm entering into the egg and fuse with it. To prevent the entering of second sperm , that is preventing polyspermy a membrane is developed around the fused sperm.  The fertilization occur at the ampula of the oviduct. The structure formed after the fusion of male and female gametes known by name spindle. The spindle consists of a diploid set of chromosomes . one pair from the mother and other from the father. The spindle also known by the name zygote . the zygote undergo further cleavage .