Reproduction in Animals

Hen reproduces through internal fertilization in which the egg is already fertilized before coming out as in form of egg.In the case of frog there is external fertilization, hence, egg fertilizes outside the female body. Female lays coverless eggs in the water body later male deposit there sperm over them. And with the help of tail, the sperm swims and fuses with egg. If these eggs have hard covering then it is impossible for the sperm to fuse with them and thus the reproduction cannot be possible.

Human female reproductive organ:

Fertilisation: the fusion of sperm and ovum is called fertilisation; it results in the formation of fertilised egg or zygote. After fertilisation the development of embryo take place. The zygote divides repeatedly to form a ball of cells, the cell then begin to form groups that develop into different tissues and organs of the body, this developing structure is called as embryo.

Reproduction is a process which is essential to maintain the life of an individual.

The organisms reproduce because of the two main reasons: -

1. To continue one's progeny
2. It provides group immortality by replacing the dead individuals with the new ones for the survival of the species on this earth.

Cloning is defined as the production of exact copy of a cell, any other living part or a complete organism. Cloning of an animal was first of all performed successfully by Lan Wilmut and his colleagues, for the first time a sheep named as dolly was cloned successfully; Dolly was born on 5 July 1996 and was the first mammal to be cloned. The process of cloning involve collection of cell from the mammary gland of a female Finn Dorsett sheep and an egg whose nucleus was removed was obtained from a Scottish blackface ewe then nucleus from the mammary gland of Finn Dorsett sheep was inserted into egg of Scottish blackface ewe, the egg thus produced was implanted into the Scottish blackface ewe, development of this egg take place normally and finally Dolly was produced.