Question

What is fertilizin and where is it produced?

Answer 1

Hint:- Sexual reproduction in human beings is accomplished by the fusion of male and female gametes. The male gamete is called sperm and the female gamete is called an ovum. Formation of sperm takes place by the process called spermatogenesis and formation of ovum occurs by oogenesis. The sperm and ovum fuses with each other and a zygote is formed. This zygote further undergoes divisions and a new offspring is formed.

Complete Answer:-
Human sperm is a microscopic structure with dimensions in micrometres. It has mainly three parts named as- head, middle piece and tail. The head of the sperm is covered by a cap called the acrosomal cap. The acrosome is a cap-like structure filled with lytic enzymes known as sperm lysins that helps in fertilisation of the ovum. In the anterior part of the middle piece, the neck is present.
The neck is narrow. It contains proximal and distal centriole. It is followed by the middle piece. In the middle piece, a spirally arranged mitochondria are present which produces energy for sperm movement. The tail of the sperm is the longest part that helps in its movement. The acrosome of the sperm contains several enzymes like hyaluronidase, corona penetrating enzyme, pro acrosin and anti fertilizin.
During the fusion of sperm with the ovum, it releases anti fertilizin and correspondingly ovum releases fertilizin. The successful binding of fertilizin with the anti fertilizin results in the penetration of sperm into the ovum. Fertilizin is produced by the zona pellucida layer of the ovum. The binding of fertilizin with anti fertilizin is a lock and key type of binding.

Note:- For the fertilisation to occur successfully, compatibility of fertilizin and anti fertilizin is necessary. Zona pellucida contains specialised receptors on which compatible sperm attaches and penetrates the ovum. This compatible sperm then fuses with the ovum and fertilisation is completed with the formation of a zygote. Successive cleavage takes place in the zygote and a new offspring is produced.