Alzheimer’s Disease, first described by Alois Alzheimer is a progressive neurodegenerative disease that causes problems with thinking, memory and behaviour (Riga et al. 2011).   According to the Alzheimer’s Association (2014) Alzheimer’s is the most common form of dementia, in which symptoms progress to become severe enough to interfere with daily activities.   Furthermore, microscopic changes begin occurring in the brain long before any clinical symptoms of dementia present.   The two primary microscopic brain lesions associated with Alzheimer’s pathology are neurofibrillary tangles and amyloid plaques, which tend to spread throughout the cortex of the brain as the disease progresses (Perl 2010).   In addition to the microscopic lesions, a brain with Alzheimer’s disease also atrophies as the disease progresses, leading to further cognitive impairment and memory loss (Riga et al. 2011).  
Neurofibrillary tangles are defined by the presence of tangles of abnormal fibers, made of the protein tau, inside the cytoplasm of pyramidal neurons (Perl 2010).   These tangles are difficult to see when a tissue sample is stained with the commonly used stain, hemotoxylin and eosin (Perl 2010).   This stain was used to stain the sample of normal cerebral cortex in Figure 1.   In order to see the neurofibrillary tangles Silver impregnation staining techniques such as modified Bielschowski, Von Braunmuhl or Gallyas techniques can be used, or one of a number of immunohistochemical techniques can also be used (Perl 2010; & Riga et al. 2011).   The histology sample in Figure 2 has been stained with a particular immunohistochemical technique in which antibodies target abnormal tau proteins within the neurofibrillary tangles to make them visible (Perl 2010).   A neurofibrillary tangle is present in Figure 2 at the tip of the red arrow.
The second brain lesions associated with Azheimer’s Disease are amyloid plaques, also called senile or neuritic plaques.   Amyloid plaques are deposits of a...