What is Fertilisation?
The process in which a male gamete fuses with a female gamete giving rise to a zygote is called Fertilisation.
Fertilisation Process
- When one sperm among all the others is able to penetrate the egg cell then the egg
releases certain chemicals. These chemicals make sure that no other sperm will now penetrate the egg. - The male nucleus from the sperm fuses with the female nucleus which is already present in the egg cell.
- The fusion stimulates a cascade of reactions which further gives rise to several successive cell divisions.
- The consecutive cell divisions then give rise to an embryo that will further develop into an organism.
What are the Types of Fertilisation?
The process of fertilisation involves the fusion of gametes. The place where the fusion of gametes can take place is different in different organisms. Depending on the location of fertilisation, it is divided into two types:
Internal fertilisation
- In this type, fertilisation occurs inside the female’s body. Hence, it is named as
Internal Fertilisation. - The sperms from a male’s body enter the female’s reproductive tract and reach
the fallopian tubes where the egg cell is present. - The fusion of both the gametes completes the fertilisation process inside the
female’s body. - All higher animals like mammals exhibit this type of fertilisation.
 External fertilisation
- In this type, fertilisation occurs outside the female’s body. Hence, it is named as
External Fertilisation. - Frogs exhibit this type of fertilisation. In this type, the unfertilized eggs are
released in the water. - The sperms from the male body will be released on these eggs and will fertilize
them. Thus, the fertilisation process will be accomplished in the water outside the
female’s body. - Many aquatic animals including fishes exhibit this type of fertilisation.
