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UND 363 Cajal
Question | Answer |
---|---|
purpose | demo astrocytes |
priciple | astrocytes are selectively stained with cajal gold sublimate |
how does this method differ from all other nervous system stains | it is done on frozen sections |
fix | formalin ammonioum bromide (no less than 2 day but no more than 25 days) |
what must be done with the fixative if the tissue was originally fixed in formalin | must be washed and placed in formalin ammonium bromide for 48 hrs |
tech | 20-30 micron, free floating, frozen sections **will section better if washed for 30 min in tap water before freezing** |
qc | cerbral cortex (NOT spinal cord) |
reagents in order of procedure | formalin ammonium bromide (fixative), gold sublimate (impregnation), sodium thiosulfate (diff'r/reducer) |
results | astrocytes with perivascular feet - black |
what type of gold chloride is preferred | brown-gold preferred over yellow gold (**must be of utmost purity**) |
what will happen to protoplasmic astrocytes after prolonged fixation | lost stainability |
what should the temp be for this stain | it should not exceed 30○C |
why is the mixture of the 2 chlorides (mercury and gold) important | If either is used alone they are not effective for demonstrating astrocytes |
how must the sections be place (or what can go wrong) | the sections must be flat and not overlap in the gold sublimate. |
what chem. is vital for successful impregnation | mercuric chloride, the mercury forms a complex with gold ions and allow them to reduce more readily. |