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UND 363 Biel PAS
UND 363 Bielschowsky PAS
| Question | Answer |
|---|---|
| Purpose | for neurofibrillary tangles and senile plaques in alzheimer disease |
| principle | ammoniacal silver impregnation (neurofibrils/axons), reduction via formaldehyde, gold toned, soduim thio to remove excess silver, schiff to stain basement membrane and amyloid in plaque |
| what will/will not occur because gold choloride was used | the background will not become yellow |
| explain the PAS reaction | Periodic acid oxidizes elements (glycols) to aldehydes, the schiff reagent reacts with aldehydes to produce a magenta color |
| fix | formalin |
| equip | chem. cleaned |
| tech | 8-10 micron |
| qc | tissue from CNS, should contain senile plaques and neurofibrillary tangles |
| procedure | ammoniacal silver impregnation, formaldehyde developed, gold toned, soduim thio silver removal, periodic acid oxidation, schiff reaction to aldehydes to form color |
| results | neurofibrillary tangles/peripheral neurites of neuritic plaques/axons - dk black, amyloid/lipofuscin - magenta |
| what is another name for neuritic plaques | senile plaques or amyloid plaques |