(August 2004) Construction a knockout mouse For decades researchers have tried to create tools that allowed for precise control over a specific gene in order to study its function. In the early 1980’s a breakthrough technology known as transgenics or gene transfer was developed [1]. This new technology involved the process of pronuclear microinjection, a method involving the injection of genetic material into the nuclei of fertilized eggs (Figure 1). Following injection, DNA would incorporate into the genome of the cell. The transformed fertilized eggs were then injected back into pregnant females and brought to term. A major downfall of…