FERTILIZATION

• The fusion of haploid male gamete, sperm and haploid female gamete, ovum is called fertilization.
• During coitus, sperm is released by male partner into the vagina of the female partner is called as insemination
• The motile sperms swim and pass the cervix to enter into the uterus and finally to reach the ovum released by the ovary in the ampulla-isthmic junction.
• Fertilization takes place in the ampulla-isthmic junction.
• All copulations do not lead to fertilization because fertilization can only occur if the ovum and sperms are transported simultaneously to the ampulla-isthmic junction.
• The sperm after reaches the ovary in the ampulla-isthmic junction comes in contact with the zona-pellucidalayer of the ovum and block the entry of the additional sperms thus only one sperm fertilizes the ovum.
• The secretions of acrosome help the sperm to enter into the ovum through zonapellucida and the plasma membrane and thus secondary oocyte completes meiosis II and results in the formation of a second polar body and haploid ovum.
• The haploid nucleus of the sperm and ovum fuse together to form a zygote which develops into new individual.

Fig. fusion of sperm and egg