Well-concerted morphogenesis and physiological activity as the whole body are realized by spatiotemporally proper functions and communications of individual cells. In this project, we aim to elucidate the mechanism of dynamic cell functions such as proliferation, migration and differentiation by inspecting them particularly in the living body. To achieve the aim, we innovate and apply the technology for in vivo optical imaging. Firstly, we create the novel probe molecules to detect the cellular activity as changes in intensity and color of fluorescence or luminescence. Secondly, we develop and improve the imaging systems that visualize the signals emitted from the probes with three-dimensionally high resolution. Ultimately, we will clarify how the cellular activity is controlled in the body by analyzing the events with mathematical models.