Congo Red Staining to Visualize Amyloid Fibrils in Cerebral Vessel Walls

Begin with a glass slide containing a paraffin-embedded brain tissue section from an elderly dog.

The tissue shows amyloid fibrils and abnormal protein aggregates in the cerebral vessel walls, which are key indicators of neurological disorders.

Dip the slide in xylene to remove the paraffin, followed by an alcohol wash to eliminate xylene.

Next, sequentially immerse the slide in decreasing concentration of alcohol. This process hydrates the tissue section and enhances its permeability for staining.

Apply Congo red dye, which binds with high affinity to the beta-sheet structure of amyloid fibrils, providing a distinct red color.

Rinse the section with water to remove the unbound dyes.

Finally, apply the basic Haematoxylin stain, which selectively stains cell nuclei in blue color. Wash to remove excess stain.

Under a microscope, dense red-stained regions in the cerebral vessel walls confirm the presence of amyloid fibrils, characteristic of cerebral amyloid angiopathy.