Summary

For most of the twentieth century, increasing numbers of genetically defined laboratory mice have been described and incorporated into biological research. Initially, research using inbred strains was limited mostly to basic genetic studies in which biochemical or visual phenotypic expression patterns were observed. With the advent of molecular genetics in the 1960s, laboratory mice developed into much more critical research tools in which the genomic basis of disease and mutation could be examined at the level of individual genes. By the 1970s, the prospect of intentionally modifying the murine genome by the addition of new functional DNA was at hand (Jaenisch and Mintz, 1974) and (Jaenisch, 1976). By the early 1980s, the persistence of microinjected laboratory-derived DNA within the cells of liveborn mice (Gordon et al., 1980) and the functional expression of transgenes in mice (Brinster, et al, 1981) and (Costantini and Lacy, 1981) were reported. Within a few years, major universities, medical schools, and a small number of pharmaceutical and biotechnology companies had created in-house transgenic mouse laboratories. Very quickly, it became apparent that the unique colony and data-management challenges of transgenic mouse operations required exceptional attention to technical detail. Expertise in transgenic colony management is critical because of the significant potential value of each transgenic lineage and the formidable housing and laboratory efforts required to develop each individual line. The mouse remains the primary choice for transgenic experimentation due to the relative ease of embryo and adult manipulation and the unparalleled depth of murine genetic knowledge. Today, transgenic mice are produced as models of human disease and toxicology, as models for transgenic livestock protocols, and as in vivo systems in which mammalian (and nonmammalian) genetic expression may be investigated.