21.3 Dementia (Major Neurocognitive Disorder)
707
B
A
D
C
Figure 21.3-2
Photomicrographs of Alzheimer’s disease neuropathology.
(A)
Deposition of insoluble fibrillar A
b
into plaques begins in the neocortex,
labeled here using an antibody against A
b
and appearing as reddish-brown deposits (
arrows
).
(B)
Bielchowsky stain of neocortex from an
individual who died in advanced stages of Alzheimer’s disease (Braak stage VI). The A
b
plaques appear as dark brown in this preparation
(
arrows
) and can be seen to be associated with dystrophic neuronal processes (
arrowheads
) in which insoluble microtubule-associate
protein
t
(MAPT) aggregates appear as black deposits. This neurofibrillary pathology also appears extensively throughout the neuropil,
and several neurofibrillary tangles can be seen (
open arrowheads
).
(C)
Bielchowsky stain of neocortex from an individual who died in
a less advanced disease stage (Braak stage IV). Although some neurofibrillary tangles are still evident (
open arrowheads
), the degree of
neurofibrillary pathology in the neuropil is substantially diminished.
(D)
Isolated neurofibrillary tangles (
open arrowheads
) in entorhinal
cortex that can be seen in normal aging (Bielchowsky stain). Notice the lack of A
b
plaques and limited neuropil involvement. (All images
obtained at 200
×
magnification and provided courtesy of Dr. Ronald L. Hamilton, Department of Pathology, Division of Neuropathology,
University of Pittsburgh School of Medicine.)
