The term humanized mouse in this text refers to a mouse in which human tissues and cells have been transplanted and show the same biological function as they do in the human body. That is, the physiological properties and functions of tra- planted human tissues and cells can be analyzed in the mouse instead of using a living human body. It should therefore be possible to study the pathophysiology and treatment of human diseases in mice with good reproducibility. Thus, the hum- ized mouse can be used as a potent tool in both basic and clinical research in the future. The development of...