Decalcification Flashcards
What is decalcification?
The removal of mineralized components from bone tissue.
Name the four methods of decalcification.
- Simple acid
- Iron exchange resin
- Electrolytic
- Chelation
What are the advantages of using simple acids for decalcification?
- Rapid decalcification
- Effective removal of calcium salts
How can the endpoint of decalcification be determined?
By monitoring the degree of decalcification through various methods.
What are the effects of over-decalcification?
Total lack of nuclear staining.
What are the effects of under-decalcification?
Tissues become difficult to cut.
Why might undecalcified bone sections be examined?
For the diagnosis of metabolic bone disease.
What are the three types of cells that contribute to bone homeostasis?
- Osteoblasts
- Osteoclasts
- Osteocytes
What is the primary function of osteoblasts?
To form new bone tissue.
What is the primary function of osteoclasts?
To resorb and break down bone.
What is the primary function of osteocytes?
To help maintain bone as living tissue.
What is the importance of fixation in the processing of bone specimens?
It protects bone and surrounding soft tissue from damage during acid decalcification.
What is the recommended fixative for bone?
10% neutral buffered formalin (NBF).
What should be done to bone specimens before exposing them to decalcifying agents?
They must be fixed.
What is a common strong acid used for decalcification?
Nitric acid (HNO3).
What is a common weak acid used for decalcification?
Formic acid (HCOOH).
What should be done to neutralize residual acid after decalcification?
- Extensive washing in tap water
- Application of alkaline solutions
- Transfer to 70% alcohol
True or False: It is safe to use heat to speed up decalcification.
False
What is produced during the dissolution of calcium carbonate with strong acids?
CO2 bubbles forming
This reaction indicates the release of carbon dioxide gas as calcium carbonate dissolves.
What effect does HCl have on collagen?
HCl causes swelling of collagen
The mode of action of HCl is similar to nitric acid.
What is the advantage of using ion exchange resins in decalcification?
Maintains hydrogen ion concentration of formic acid and preserves cellular details
This method is superior to regular acid decalcification.
What is the principle behind electrolytic decalcification?
Positively charged calcium ions migrate to the negative electrode
This method can decalcify bone specimens in 2-6 hours.
What is the main chelating agent used in histology?
Ethylenediaminetetraacetic acid (EDTA)
EDTA binds calcium into a soluble non-ionizable compound.
What method is used for determining the endpoint of decalcification?
Chemical method
This method detects the presence of calcium released from bone.
What indicates that decalcification is complete when using the chemical method?
The solution must remain clear for 5 minutes
Turbidity indicates the presence of calcium.
What is the best and most accurate method to check decalcification endpoint?
X-rays
X-rays can show opaque areas where calcium deposits remain.
What is the problem with using probing as a method for endpoint determination?
It is not recommended due to potential tissue damage
Probing lacks accuracy and can create histologic artifacts.
What embedding medium is commonly used for undecalcified bone?
Glycol methylcrylate
This medium is suitable for sections ground to 75-100um.
How can bone dust during cutting be prevented?
By trimming surfaces post decalcification and using a diamond blade knife
This helps maintain the integrity of the specimen.
