Animal cloning

Animal cloning

The process of making desirable animals by cloning is called animal cloning. It is a difficult process than plant cloning because the animal cells lose their totipotency on reaching the gastrula stage of animal development.

The first animal cloning was made by Robert Briggs and Thomas King in 1952. They cloned frogs from tadpole cells. In 1962 John Gurdon also cloned frogs using cells from older tadpoles.

Dr. Ian Wilmut in1996 has created a sensational news in the field of reproductive biology by cloning a fully viable mammal, the Dolly. Her creation raised a troubling question can humans, too, be cloned?

Ian Wilmut (Roslin Institute, Edinburgh, Scotland) took cells from the udder (mammary glands) of a 6 - 7 year old female sheep (Finn Dorset Ewe). These cells are transferred to a culture medium devoid of nutrients. This halted the starved cells from dividing and switched off their active genes. Meanwhile, an unfertilized egg was collected from another sheep (Scottish Blackface Ewe) and its nucleus was sucked out leaving an empty cell containing all the necessary materials to produce an embryo. The nucleus of the udder cell was separated and transferred to the non -nucleated egg cell. Then he fused the udder cell nucleus with the empty egg cell by mild electrical stimulation. The fused cell began to develop. At 32 :ell stage the embryo was transferred into the womb (uterus) of a surrogate mother ( substitute mother) of the same breed (Scottish Black Face Ewe) from which the egg was taken. After five months, the lamb was born. This first successful animal clone was named Dolly. She was genetically identical to the mother sheep from which the nucleus of the udder cell was taken. Later Dolly conceived in natural way and gave birth to a lamb named Bonny. This proves that an animal clone can lead a normal life.

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