In this article we will discuss about the meaning of transgenic mice.
Cloned genes can be introduced into the germ line cells of an animal allowing study of the intact animal rather than in cultured cells. For this purpose, the nucleus in mouse embryonal cells has been used for injecting foreign DNA. The goal in such experiments is to have the foreign DNA integrated into the egg’s chromosomes.
Cell divisions in the egg will pass on the foreign DNA to all cells of the embryo and subsequently to the adult animal. Mice that have been genetically engineered to carry such foreign genes in their chromosomes are called transgenic mice. To generate transgenic mice, cloned DNA is microinjected into a pro-nucleus of the fertilised egg (Fig. 24.2).
The eggs are then transferred to foster mothers and allowed to develop to term. Among the progeny mice, about 10% will have the foreign DNA integrated into the genome of the fertilised egg, and therefore, in all cells of the adult mice. Since the foreign DNA is also present in the germ line cells of the progeny mice, these mice are mated to breed new progeny mice which would inherit the foreign DNA.