Question

What is Zona Reaction.

Answer 1

Hint: Zona pellucida is the natural inducer of the acrosome reaction. The acrosome reaction must occur before the sperm cell reaches the zona pellucida. The zona pellucida and membrane of the oocyte is digested by the acrosin. The zona pellucida releases Calcium granules to prevent other sperm from binding.

Complete answer:
Zona reaction corresponds to the change of the zona pellucida while responding to fertilization. This changes the binding and solubility attributes of the zona pellucida , resulting in a slow block to the polyspermy.

During oogenesis, the zona pellucida establishes the communication between the follicle cells and the egg cells, which helps in protecting the eggs, oocytes, and embryos. It checks the activity between the ovulated eggs and free-swimming sperm before and during.

The importance of the zona reaction is that it represents the major block to polyspermy in most mammals. This effect is the result of two measurable changes induced in the zona pellucida: the zona pellucida hardness and sperm receptors in the zona pellucida are destroyed.

Additional information: The sperm on maturation develops a tail and swims freely to reach the ovum. The sperm head releases the acrosome which helps in entering the ovum.The loss of sperm receptors can be presented by mixing sperm with both unfertilized oocytes and two-cell embryos. The sperm attaches to the zona pellucida of oocytes and does not bind to the two-cell embryos.

Note: Fertilization is the process of combining the male gamete (sperm), with the female gamete (ovum). The product of fertilization is a cell called a zygote. Also note that Oocytes which have not yet undergone the zona reaction are called unfertilized oocytes.