PROJECT SUMMARY AD is a complex, progressive neurodegenerative disease and is the most common cause of dementia among the elderly. It has a clear spatial and temporal progression; multiple lines of evidence show that the degeneration patterns seen in AD are not random but show a characteristic anatomical sequence as the pathology advances over decades. The mechanisms that cause these spatial patterns are poorly understood and basic questions about the relative contributions of microscopic molecular mechanisms versus macroscopic anatomical changes in driving AD progression remain unclear. Unfortunately, whole brain techniques like MRI lacks the necessary molecular contrast and resolution to answer these questions. Histology can reveal the microscopic, molecular signatures, but is constrained to small 2D sections due to technical limitations with large scale histology, particularly 3D histology. These limitations make it difficult to map AD progression and limit the usefulness of post-mortem tissue that might reveal crucial clues about AD. In this proposal we will address this barrier by providing a fee-for-service sectioning, slice mounting, staining, and imaging platform that will offer non-specialized labs the ability to obtain high quality 3D serial section reconstructions of post-mortem human brains up to entire hemispheres. Specimens can be sent to TissueVision where they will be sectioned at thicknesses ranging from 50 microns to 2 mm, with alternating block face imaging between sections to help facilitate 3D reconstruction. Each mounted section is available for further staining and digitization at high resolution with Whole Slide imaging (WSI) and served over the cloud to the client with optional 3D modeling. The physical sections can be returned to the client or stored for further follow-up analyses. This proposal combines expertise in microscopy and 3D histology at TissueVision with world- class clinical researchers at Indiana University and builds on existing work at TissueVision. The section capture and slide mounting is based on existing technology contained within our TissueCyte 1600FC STPT platform for mouse and rat brains. We also build on a strong collaboration with Jackson Labs and the MODEL-AD center with an existing TissueVision Phase II NIA SBIR to map AD spatial progression in mouse model brains. We will extend the collaboration to clinical collaborators at the Model-AD at Indiana University who will be supplying post-mortem human tissue and providing guidance and feedback on the histological quality. While our focus is on AD in this project, the proposed technology will have broad impact across a wide range of disciplines, from cardiac biology, infectious diseases, cancer, and basic research.