neuropathology Flashcards
histology stains ( 3 categories)
Stains fall into one of three categories:
Neuronal cell bodies & processes
Glial cells and processes
Myelin sheath
nerve cell processes
axons
dendrites
Axons Long and myelinated Carry impulse away from cell body Also referred to as nerve fibers Dendrites Short No myelin
Nissl substance
Basophilic material in the neuron cytoplasm
Rough Endoplasmic Reticulum & RNA
Injury causes disappearance (around the nuclei first)
Nissl staining
Achieved with Basic aniline dyes such as thionin and cresyl echt violet
Neuroglia
Supporting network of the CNS (nerve glue)
No connective tissue in the CNS outside of blood vessels and meninges
Surround neurons to provide insulation & support
Myelin is produced by glia
glial cells
Oligodendroglia-most numerous, produces myelin
Astrocytes-following injury
Microglia-fixed phagocytic cells
Ependymal Cells- epithelial cells that line ventricles and spinal cord
Not frequently stained in clinical labs
myelin
White, fatty, non-living proteolipid
Most is lost through processing
Neurokeratin, a proteolipid, is left
Stained by Luxol Fast Blue & Iron Hematoxylin
staining methods for nissl substance
Cresyl echt violet, Cresyl Violet & Cresyl fast violet refers to same dye
Basic dye which stains nucleic acids
Variation in the pH & differentiation determines whether just nissl or nissl and nuclei will be stained
May be combined with other stains to stain nissl and myelin
Control – spinal cord 6-8 µm
Bodian Method forNerve fiber, endings or fibrils
dont really use anymore & takes a long time
Bodian method – a silver technique which uses PROTARGOLTM a silver proteinate containing copper
Argyrophil method using hydroquinone & formaldehyde as reducer
Tone in gold chloride
Stains nerve fibers
Protargol a silver proteinate and copper in the impregnation solution- 48 hours
Reduced with hydroquinone & formaldehyde(1st)
Reduction of gold chloride with oxalic acid (2nd)- reduced twice
Holmes silver Nitrate
Method for nerve fibers & neurofibrils
Sections 10-15 µm are sensitized with 20% silver nitrate
Impregnation solution contains less silver (1%)
Reduce in hydroquinone & sodium sulfite (developer)
Tone in gold chloride
Reduce gold in oxalic acid
Hypo to remove unreduced silver
Control – cerebral cortex
Bielschowsky
Methods with and without PAS
Silver method used for Alzheimer’s detection
Neurofibrillary tangles
Senile plaques (amyloid)- PAS
Hypo
Periodic acid ( generates aldehydes)
Schiffs ( demonstrates aldehydes)
Notes on brain sections:
Tend to come off slide ( use adehesive; albumin)
Use adhesive and dry overnight at 37°C
Cut at 6-8 µm
Bielschowsky steps
Slides first placed in 20% silver (like Holmes)
Next ammoniacal silver solution which is prepared titration like (similar to reticulin)
Wash in ammonia water Add reducer (developer) formaldehyde & acid to the ammoniacal silver
Place slides & watch usually 3 minutes
Gold chloride
Gallayas
Still another silver method for Alzheimer’s
Method is included in your outline
NO amyloid detection
Abnormal Tau protein detection
Alzheimer study
Features include 1neurofibrillary tangles, 2amyloid plaques, and 3tau protein***
Bielschowsky 1&2
Gallya 1&3
Congo red- amyloid
Immunohistochemistry for tau, ubiquitin & chromogranin
- neuroendocrine tumors
Immunohistochemical markers
Tau protein – a filament in neuronal tissue
β amyloid – abnormal protein found in senile plaques
An abnormal Tau protein and β amyloid are both involved in Alzheimer disease process
Ubiquitin – found in neurofibrillary tangles of Alzheimer disease
GFAP – Glial fibrillary acidic protein. Gives strength to glial cells such as astrocytes( supports neurons)
Chromogranin – elevated in neuroendocrine tumors
