Question

Explain the process of fusion of gametes in humans.

Answer 1

Hint:Two stages take place in the fertilization of gametes. Acrosomal reaction and cortical reaction are the stages that occur in the process of fertilization.

Complete answer:
To answer this question, first, we need to know about gametes. Gametes are the reproductive cells used to create a new organism, called a zygote, during sexual reproduction. The gametes are distinct in males and females. The sperm is called male gamete. It is much smaller, and more mobile than the female gamete. The female gamete is an egg or ova. It is much larger than the sperm, and would not move. The gametes are haploid cells, as they only have one set of chromosomes. They will combine their single sets of chromosomes to make a complete set of chromosomes, and then they will be known as diploid cells.

Gametes are reproductive haploid cells that are produced during sexual reproduction. Fusing a male gamete (sperm) with a female gamete (ovum) is called fertilization and allows a diploid zygote to form. The fertilization process primarily takes place in two stages, the first being the 'acrosomal reaction' and the second being the 'cortical reaction.' When a sperm enters the female genital tract, it migrates into the Fallopian tube toward the ovum. When it reaches the ovum, it receives signals from the ovum and thus releases digestive enzymes from the sperm, acrosome that helps the sperm penetrate the zone pellucid that is the glycoprotein layer that surrounds the plasma membrane of oocytes and fuse with the oocyte membrane. The first sperm cell to connect with the ovum's plasma membrane fuses with it in the cortical reaction. The sperm pronucleus now fuses in its cytoplasm with the pronucleus of the ovum, thereby combining two sets of haploid genetic material and creating a totipotent diploid zygote.

Note: In acrosomal reaction, the digestive enzyme of sperm called acrosome helps to penetrate the zona pellucida and in the cortical reaction, the first sperm cell is fused with the plasma membrane of ovum.