Decalcification Flashcards
Give the two chemical agents usually used to carry out decalcification.
- Chemical agents with acids
2. Chemical agents with chelating agents
Inadequate decalcification will result in?
Poor cutting of hard tissues and damage to the knife
What is the remedy if there is a “grating” sensation when sectioned?
Place the block face down on a pad of cotton or gauze saturated with 10% HCL for 1hr
True or false:
A good decalcifying agent must be capable of removing calcium salts from tissues with a little destruction of cells and tissue components
False. There should be no destruction of cells and tissue components
True or false:
Decalcification should be done before fixation and before impregnation
False. Decalcification is done AFTER fixation and before impregnation
Calcium may be removed by? Give four agents
- Acids
- Chelating agents
- Ion exchange resins
- Electrophoresis
Most widely used decalcifying agents for routine decalcification of large amounts bone tissues
Acid decalcifying agents
True or false:
Acid decalcifying agents are stable, easily available and relatively inexpensive
True
Most common and very rapid decalcifying agent which can be used both as a simple aqueous solution or combined with other agents
Nitric acid
Recommended for urgent biopsy, needle and small biopsy specimen to permit rapid diagnosis within 24hrs or less.
Aqueous Nitric acid add solution 10%
Decalcification time of formol-nitric acid
1-3days
What should you do if there is a yellow discoloration in the specimen due to formol-nitric acid?
Neutralize the tissue with 5% sodium sulfate and washing in running tap water for at least 12 hrs or by add 0.1% urea to pure concentrated nitric acid
Decalcification time of Perenyi’s fluid
2-7days
Most rapid decalcifying agent
Phloroglucin-nitric acid
Decalcification time of Phloroglucin-nitric acid
12-24hrs
When decalcification with phloroglucin-nitric acid is complete, the acid must be removed by?
Three changes of 70%-90% ethanol
Decalcifying agent recommended for teeth and small pieces of bone
Von Ebner’s fluid
True or false:
Von ebner’s fluid requires washing out
False
The only weak acid used extensively as a primary decalcifying agent
Formic acid
Can be both used as a fixative and decalcifying agent
Aqueous formic acid
Decalcification time of aqueous formic acid
2-7days
True or false:
Aqueous formic acid does not require neutralization
False
Recommended for autopsy materials, bone marrow, cartilage, and tissues studied for research purposes
Formic-acid sodium citrate solution
Decalcification time of formic acid-sodium citrate solution
3-14days
Decalcification time of trichloroacetate acid
4-8 days
It tends to undergo reduction and forms precipitate ls at the bottom of the container thus requiring frequent change ls of solution
Chromic acid
Other name for chromic acid
Flemming’s fluid
Are substances which combine with calcium ions and other salts to form weakly dissociated complexes and facilitate removal of calcium salt
Chelating agents
Most common chelating agent
EDTA/ Versene
For how long should small specimen be immersed in EDTA?
1-3weeks
How long would it take to totally decalcify dense cortical bone with EDTA?
6-8weeks
Excellent bone decalcifier for immunohistochemical or enzyme staining and/or for electron microscopy
Chelating agents
What can be used to restore/reactivate alkaline phosphatase activity that has been inactivated by EDTA?
Addition of magnesium chloride
Hastens decalcification by removing calcium ions from formic acid-containing decalcifying solutions
Ion exchange resin
True or false:
Ion exchange is recommended for fluids containing mineral acid (nitric or hydrochloric)
False. Not recommended
For how long are tissues allowed to stay in solution when using ion exchange resin?
1-14days
A process whereby positively charged calcium ions are attracted to negative electrode and subsequently removed from decalcifying solution
Electrophoresis
Method in measuring the extent of decalcification
- Physical/ mechanical
- X-ray/ radiological
- Chemical/ calcium oxalate test
Acts as a delcifying agent and tissue softener
Perenyi’s fluid