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These laboratory sessions are devoted to the grand themes of pathology: circulatory disorders, infections, and neoplasia. In addition, we will study several disorders unique to the nervous system.
The three neuropathology laboratories are divided into (1) cerebral vascular disease; tumors; (2) infectious diseases; toxic, metabolic, and demyelinating diseases; and (3) dementia and neurodegenerative diseases; spinal cord diseases.
The Review of Normal Microscopic Anatomy and Neurohistology page contains seven normal brain sections to help you "review" macroscopic anatomy and normal histology as seen in the frontal cortex, two views of the basal ganglia (striatum), hippocampus and temporal lobe, midbrain, pons, and medulla with cerebellum.
Unlike the previous pathology sections that were stained with hematoxylin and eosin, a variety of special stains are used in neuropathology. Below is a brief description of these stains.
Luxol - The Luxol fast blue stain, short for Luxol fast blue, cresyl violet and eosin, is really good for staining myelin. Myelin stains blue. Nissl substance and nuclei stain purple, and nearly all else, including the axis cylinders, cytoplasm of the cells, glial fibers, collagen, and red cells, stain pink. (RBCs and collagen may unavoidably stain blue.)
PTAH - This is short for phosphotungstic acid hematoxylin. With this stain, myelin stains blue-purple, nuclei and Nissl substance stain dark purple-blue, axis cylinders and cytoplasm stain pink or brown, and glial fibers stain deep blue. Collagen stains scarlet or orange, and RBCs stain blue. This is a really nice stain to show glial fibers.
H&E - Our workhorse stain. Myelin stains dark pink, nuclei and Nissl substance blue-purple, and everything else pink. RBCs are reddish orange.
Trichrome - This stain colors myelin orange, nuclei and Nissl substance purple-black, axis cylinders, glial fibers, and other cytoplasm brown-orange. Collagen is stained green and red cells turn orange.
Bielschowsky - This is a gorgeous stain that is used almost exclusively to outline tangles and plaques (which stain black against a gold background). This silver stain colors axis cylinders and neurofibrils black, cytoplasm and nuclei tan to light brown, blood vessels yellow, tan, or brown, and RBCs tan to dark brown. The background or neuropil is a pale tan to yellow (or gold). Glial fibers are usually not stained.
Tau Immunostain - characterizes the accumulation of the microtubule-associated protein tau, which stains a dark brown in the section. Disorders staining positive are known as tauopathies.
Alpha (α) Synuclein Immunostain - characterizes the accumulation of the synaptic-associated protein alpha synuclein, which stains dark brown in the section. Disorders staining positive are known as alpha synucleinopathies.
Αβ Immunostain - characterizes the presence of a peptide (Αβ) derived from a fragment of a normal neuronal protein termed APP (amyloid precursor protein), which stains dark brown in the section.