Abnormalities of the tumor vasculature and their consequences on the microenvironment of tumor cells impact on tumor progression and response to both blood-borne anti-cancer agents and radio-therapy, as well as making tumor blood vessels a target for therapy in their own right. Intravital microscopy of experimental tumors, most commonly grown in ‘window’ chambers, such as the dorsal skin fold chamber in mice and rats, enables investigations of tumor microcirculatory function. This is needed both to understand the molecular control of tumor vascular function and to measure the response of the vasculature to treatment. In particular, intravital microscopy enables parameters associated with blood supply, vascular permeability and oxygenation to be estimated, at high spatial and temporal resolution. In this chapter, methods used for measuring a range of these parameters, specific examples of their applications, the significance of findings and some of the limitations of the techniques are described
