Isolation, Microinjection, and Transfer of Mouse Blastocysts

Over the last half century, the efforts of several pioneering developmental biologists have established the conditions to culture, manipulate, and reintroduce mouse embryos that will successfully develop to term. The isolation of teratocarcinoma cell lines, first, and later of blastocyst-derived embryonic stem (ES) cell lines that can contribute to the germ line of recipient mouse embryos has provided the basis for a system to introduce targeted mutations into the mouse genome (for a historical review see ref. 1 . Today, the technology to produce genetically manipulated mice has been made more accessible to investigators by the emergence of a biotechnology industry that provides high-quality instrumentation, materials, and reagents. However, specific technical skills still need to be acquired by the investigator in order to employ successfully this technology for the production of genetically engineered mouse models.