Transgenic Mice - Mouse is the most preferred mammal for studies on gene transfers due to its many favourable features like short oestrous cycle and gestation period, relatively short generation time, production of several offspring per pregnancy (i.e., litter), convenient in vitro fertilization, successful culture of embryos in vitro at least for a period of time, production and maintenance of ES cell lines, availability of a diverse array of genetic stocks, etc.

As a result, the techniques for gene transfer and transgenic production have been developed using mice as models; subsequently, these approaches have been modified to adapt them to other animal species. More recently, rats and rabbits are being increasingly used for research work on gene transfer.