Production of Transgenic Mice

The term “transgenic ” has been used since the beginning of the 1980s to define animals that had incorporated foreign DNA into their genome (1 ,2 ).Currently, transgenic animals include various species such as fish,poultry,rats,rabbits,pigs, sheep,goats,cattle,and mice (3 ,4 ).Mice remain the preferred system for exploring new trends in transgenic research mainly because they are easy to maintain,have short generations (6 –8 wk on average),and produce large numbers of progeny (eight on average).Although gene transfer into mice can be achieved by several methods,such as retroviral infection,embryonic stem (ES)cell transfer or cell/embryo aggregation, the direct microinjection of purified DNA into the male pronucleus of fertilized mouse oocytes has been the most widely used technique for generating transgenic mice,with a rate of 5–30%of the pups born harboring the transgene (5 ).Several books and review articles have discussed many aspects of this technology,and they provide good references for further readings (3 –11 ).