Decalcification Flashcards
What is decalcification
the process of removing calcium from tissue
What is usually used to decalcify
acid
At what pH are calcium salts soluble
4.5
In what state must tissue be before decalcification
fixed
How can you decalcify and fix at the same time
using formic acid and formalin
Why must tissue be washed before and after decalcification with hydrochloric acid
Formalin and HCL react to produce bischloromethyl ether which is an extremely hazardous carcinogen
What is the process for simple acid decalcification
tissue is submerged. agitation is recommended to prevent the solution surrounding the tissue from being saturated with calcium ions
What is the process for ion-exchange resins decalcification
resins exchange ammonium ions for calcium ions preventing the solution from becoming saturated
What is the process for EDTA decalcification
chelating agents selectively bind metal ions from the tissue without affecting other tissue components
How does endpoint detection using chemical detection work
an aliquot of decalcifying solution is neutralized with ammonium hydroxide and then reacted with an equal volume of saturated ammonium oxalate. Any calcium ions present will react forming a white precipitate which means that calcium persists in the tissue
How does endpoint detection using radiography work
calcium is radio-opaque so it can be determined if there is any remaining in the tissue
How does endpoint detection using physical methods work
through bending, probing or attempting to cut the sample. Though it is fast and easy it is unreliable
What is an important step in decalcification
neutralization of residual acid
What occurs if tissue is underdecalcified
obvious scores and tears will be noted in areas of the block. If large enough calcium deposits remain then there may be resistance in the hand wheel
What is surface decalcification
once the block is faced it is placed cut side down in strong acid for 15-30 minutes then washed well in running water and then attempted to cut
