What are transgenic animals?

Transgenic animals:

1. Animals such as mice, fish, and pigs whose genome has been altered in a heritable manner by introducing foreign DNA into the genome of a zygote or developing embryos of these animals.
2. Transgenic animals are also called Genetically modified organisms, as their genome has been modified by adding foreign gene.

Two methods are used to create transgenic animals:

DNA Microinjection:

1. The most primitive method to create transgenic animals.
2. In this method, the desired DNA sequence ( transgene) is injected into the zygote of mice after fertilization.
3. As the transgene gets incorporated with the genome of the zygote, it gets developed into a transgene animal.

Somatic cell nuclear transfer:

1. Due to some of the drawbacks of DNA microinjection, this method was developed through which the somatic tissue of mice is isolated in the lab and cultured to get somatic cells.
2. The somatic cell is made enucleated and its nucleus is fused with the recipient egg cell.
3. The recipient egg cell is made enucleated by removing the nucleus from the egg cell.
4. The somatic cell nucleus is fused with enucleated egg cells by giving electrical impulses.
5. The developing, embryo is allowed to develop till the blastocyst stage and implanted in the surrogate mother for further development.