DECALCIFICATION Flashcards
is the removal of calcium ions from the bone through histological process thereby making the bone flexible and easy for pathological investigation.
Decalcification
The removal of_____ deposits is essential for good embedding procedure as well as to obtain soft sections of the bone using the microtome.
calcium
is usually cared out between the fixation and dehydration. Bone must obviously be processed in this way, but other tissues may also contain calcified areas.
Decalcification
Strong mineral acids such as_______ and ______ are used with dense cortical bone because they will remove large quantities of calcium at a rapid rate. However, these strong acids also damage cellular morphology.
nitric and hydrochloric acids
Mineral acid decalcifiers are not recommended for delicate tissues such as______ because they are not as aggressive, organic acids such as_______ are better suited to bone marrow and other soft tissues.
bone marrow
acetic and formic acid
act more slowly than mineral acids, and will require extended treatments to decalcify cortical bone.
Organic acids
Formic acid in a ______ concentration is the best all-around decalcifier.
Some commercial solutions combine formic acid with formalin to fix and decalcify tissues at the same time.
10%
Chelating agents such as______ can remove calcium and is not as harsh as mineral or organic acids.
ethylenediaminetetracetic acid (EDTA)
The use of EDTA is limited by the fact that it penetrates tissue and works slowly so it is not suitable for urgent specimens.
It is used at a concentration of approximately_____ as a neutralized solution.
14%
The rate at which EDTA will decalcify is_____ dependent.
It is generally used at_____. It works more rapidly at____ but some tissue elements can be damaged at alkaline _____.
pH
pH7.0
pH10
pH10
Techniques For Increasing The Efficiency Of Decalcification
Microwave treatment
lon-exchange resins
Electrolytic decalcification or electrolysis
has been used with hydrochloric acid decalcifiers but the raised temperature may damage morphology and cause staining artefacts.
Microwave treatment
have been incorporated into some decalcification protocols.
They are added to the container holding the decalcifier and take up the ionized calcium maintaining the effectiveness of the acid.
If acid decalcifiers are used in adequate volumes and replaced regularly the use of such resins is probably unnecessary.
lon-exchange resins
is done by placing the bone in acid decalcifier and attached to an electrode through which current is applied.
Experimental situations showed calcium was removed with the least tissue damage.
However, it has not found wide acceptance because of the potential to cause heat damage to the specimen.
It is a slow process and not suited for routine daily use.
Electrolytic decalcification or electrolysis
Factors Influencing The Rate Of Decalcification
• Concentration and Volume
• Temperature.
• Agitation.
• Tissue Size and Consistency.