Generation of Transgenic Mice by Pronuclear Injection

Over the past decades, transgenic mice have become a valuable tool in investigating gene expression, regulation, and function. Mouse models have been established for various human diseases to determine gene expression patterns and to elucidate gene function in tissues and organ systems. However, the outcome of a particular transgenic experiment is affected by a variety of factors that are only partly understood. Expression of transgenes may occur at ectopic sites, mouse lines generated might not express the transgene at all, or expression levels may decrease with increasing number of generations (see Note 1 ). Some of these difficulties can be solved by carefully planning the experiment. Thus the following chapter will not only deal with practical aspects of the microinjection but intends to provide guidelines for setting up a transgenic experiment.