
The author introduces MOCAT as a method to efficiently clear and label FFPE brain tissues, enabling comprehensive 3D analyses. By optimizing antigen retrieval with heat-induced methods, MOCAT allows for deep immunolabeling and volumetric quantification of neuronal circuitry in archived specimens.


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Tissue clearing and labeling techniques have revolutionized brain-wide imaging and analysis, yet their application to clinical formalin-fixed paraffin-embedded (FFPE) blocks remains challenging. We introduce MOCAT, a novel method for efficiently clearing and labeling centimeter-thick FFPE specimens using elevated temperature and concentrated detergents. MOCAT with multi-round immunolabeling reveals neuron circuitry regulating multiple neurotransmitter systems in a whole FFPE mouse brain, and is able to be used as the evaluation of disease treatment efficiency. MOCAT also supports expansion microscopy and can be performed on a non-sectioned 15-year-old FFPE specimen. Thus, MOCAT represents a feasible approach for researching archived FFPE specimens for future neuroscientific and 3D neuropathological analyses.

### Competing Interest Statement

The authors have declared no competing interest.

The raw data that support the findings of this study are available upon request.

Revealing intact neuronal circuitry in centimeter-sized formalin-fixed paraffin-embedded brain

a-novel-method-for-clearing-and-labeling-ffpe-brain-tissues


A Novel Method for Clearing and Labeling FFPE Brain Tissues
