The black stained structure in the center of the image is identified as which of the following?

• A. Senile plaque
• B. Lewy body
• C. Neurofibrillary tangle
• D. Amyloid angiopathy

Answer: (A)

The structure shown is best identified as a senile plaque. These are extracellular deposits of beta-amyloid that form a dense core often surrounded by a halo of neuritic processes. In histology or special-stain images, such plaques appear as dark or black rounded areas in the brain parenchyma, typically in gray matter like the cortex or hippocampus. This extracellular location and core-halo morphology distinguish senile plaques from other inclusions: Lewy bodies are intracellular inclusions of alpha-synuclein inside neurons, neurofibrillary tangles are twisted, thread-like tau filaments inside neurons, and amyloid angiopathy involves amyloid deposition within the walls of blood vessels rather than as a parenchymal plaque.