Figure 2 A blastocyst of a mouse into which genetically engineered embryonic stem cells from another mouse are injected. Photography courtesy of Anne Bower and Manfred Baetscher, Transgenic Core, Oregon Health and Science University, Portland, OR

Figure 2 A blastocyst of a mouse into which genetically engineered embryonic stem cells from another mouse are injected. Photography courtesy of Anne Bower and Manfred Baetscher, Transgenic Core, Oregon Health and Science University, Portland, OR