ABSTRACT – Core B The imaging and surgical core will provide state-of-the-art imaging services to the program. Dr. Randolph’s experience in organizing collaborative teams and her laboratory's background in macrophage biology and lymphatic/vascular trafficking of immune cells and lipoproteins will facilitate applications in imaging that will be tailored to the science of each project. The core will incorporate major contributions from highly expert co- investigators. Dr. Bernd Zinselmeyer is an expert in multiple modalities of light microscopy, including its application in studies of the CNS. He will contribute several lines of expertise in the grant, from confocal and 2- photon microscopy to high-speed epifluorescence imaging. Dr. Song Hu is an innovator in photoacoustic imaging with demonstrated expertise in using this technology to study the vasculature of the CNS. Dr. Igor Smirnov is an expert microsurgeon who will provide and oversee highly skilled surgical manipulations for the projects, including procedures like skull transplant and skull thinning. These co-investigators bring more than their state-of-the-art expertise; they also all bring demonstrated collaborations with one or more project leaders. By working together, this core team of investigators and affiliated staff will offer to all projects the following range of expert surgical procedures and imaging applications. The aims of the imaging and surgical core are to (1) carry out deep-tissue imaging of meninges and outer regions of the brain, (2) apply combinatorial methods (2-photon, high-speed widefield, and photoacoustic imaging) for intravital imaging to investigate macrophage behavior and blood flow dynamics in the meninges, and (3) employ established and novel tools to quantify molecular outflow from the meningeal space.