ABSTRACT: Organ Specific Project Beyond nutrient absorption, the gastrointestinal tract has wide-ranging effects on the normal and diseased physiologies of other organ systems, including metabolism, neural function, and the immune system. A high-resolution, multi-modal 3D map of the bowel would be an invaluable resource to understand normal bowel function and the perturbations that lead to disease. Our continued goal is to create this map along the length of the small bowel and colon, both of which have nuanced geographic specializations of function. Using single-nuclei RNA+ATAC-seq, we will simultaneously profile the gene expression and regulatory programs that define the complex cell populations that drive bowel function. We will use the CODEX multiplex immunoassay to define the spatial relationships of these cell populations and to create 3D maps using serial sections. We will also use the Molecular Cartography multiplex FISH assay to generate transcript spatial maps to better integrate the single-nuclei data to the CODEX immuno-maps. These investigations will be performed on tissues that are preserved and procured in a manner suitable for high-quality molecular map generation. Our target milestone is to characterize six bowel sites from a total of 8 demographically-diverse individuals at full coverage. To generate deeper coverage maps in more individuals, two bowel sites will be mapped at light coverage in 20 individuals.