Decalcification

Question 1

Give the two chemical agents usually used to carry out decalcification.

Answer 1

1. Chemical agents with acids

2. Chemical agents with chelating agents

Question 2

Inadequate decalcification will result in?

Answer 2

Poor cutting of hard tissues and damage to the knife

Question 3

What is the remedy if there is a “grating” sensation when sectioned?

Answer 3

Place the block face down on a pad of cotton or gauze saturated with 10% HCL for 1hr

Question 4

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

Answer 4

False. There should be no destruction of cells and tissue components

Question 5

True or false:

Decalcification should be done before fixation and before impregnation

Answer 5

False. Decalcification is done AFTER fixation and before impregnation

Question 6

Calcium may be removed by? Give four agents

Answer 6

1. Acids
2. Chelating agents
3. Ion exchange resins
4. Electrophoresis

Question 7

Most widely used decalcifying agents for routine decalcification of large amounts bone tissues

Answer 7

Acid decalcifying agents

Question 8

True or false:

Acid decalcifying agents are stable, easily available and relatively inexpensive

Answer 8

True

Question 9

Most common and very rapid decalcifying agent which can be used both as a simple aqueous solution or combined with other agents

Answer 9

Nitric acid

Question 10

Recommended for urgent biopsy, needle and small biopsy specimen to permit rapid diagnosis within 24hrs or less.

Answer 10

Aqueous Nitric acid add solution 10%

Question 11

Decalcification time of formol-nitric acid

Answer 11

1-3days

Question 12

What should you do if there is a yellow discoloration in the specimen due to formol-nitric acid?

Answer 12

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

Question 13

Decalcification time of Perenyi’s fluid

Answer 13

2-7days

Question 14

Most rapid decalcifying agent

Answer 14

Phloroglucin-nitric acid

Question 15

Decalcification time of Phloroglucin-nitric acid

Answer 15

12-24hrs

Question 16

When decalcification with phloroglucin-nitric acid is complete, the acid must be removed by?

Answer 16

Three changes of 70%-90% ethanol

Question 17

Decalcifying agent recommended for teeth and small pieces of bone

Answer 17

Von Ebner’s fluid

Question 18

True or false:

Von ebner’s fluid requires washing out

Answer 18

False

Question 19

The only weak acid used extensively as a primary decalcifying agent

Answer 19

Formic acid

Question 20

Can be both used as a fixative and decalcifying agent

Answer 20

Aqueous formic acid

Question 21

Decalcification time of aqueous formic acid

Answer 21

2-7days

Question 22

True or false:

Aqueous formic acid does not require neutralization

Answer 22

False

Question 23

Recommended for autopsy materials, bone marrow, cartilage, and tissues studied for research purposes

Answer 23

Formic-acid sodium citrate solution

Question 24

Decalcification time of formic acid-sodium citrate solution

Answer 24

3-14days

Question 25

Decalcification time of trichloroacetate acid

Answer 25

4-8 days

Question 26

It tends to undergo reduction and forms precipitate ls at the bottom of the container thus requiring frequent change ls of solution

Answer 26

Chromic acid

Question 27

Other name for chromic acid

Answer 27

Flemming’s fluid

Question 28

Are substances which combine with calcium ions and other salts to form weakly dissociated complexes and facilitate removal of calcium salt

Answer 28

Chelating agents

Question 29

Most common chelating agent

Answer 29

EDTA/ Versene

Question 30

For how long should small specimen be immersed in EDTA?

Answer 30

1-3weeks

Question 31

How long would it take to totally decalcify dense cortical bone with EDTA?

Answer 31

6-8weeks

Question 32

Excellent bone decalcifier for immunohistochemical or enzyme staining and/or for electron microscopy

Answer 32

Chelating agents

Question 33

What can be used to restore/reactivate alkaline phosphatase activity that has been inactivated by EDTA?

Answer 33

Addition of magnesium chloride

Question 34

Hastens decalcification by removing calcium ions from formic acid-containing decalcifying solutions

Answer 34

Ion exchange resin

Question 35

True or false: | Ion exchange is recommended for fluids containing mineral acid (nitric or hydrochloric)

Answer 35

False. Not recommended

Question 36

For how long are tissues allowed to stay in solution when using ion exchange resin?

Answer 36

1-14days

Question 37

A process whereby positively charged calcium ions are attracted to negative electrode and subsequently removed from decalcifying solution

Answer 37

Electrophoresis

Question 38

Method in measuring the extent of decalcification

Answer 38

1. Physical/ mechanical 2. X-ray/ radiological 3. Chemical/ calcium oxalate test

Question 39

Acts as a delcifying agent and tissue softener

Answer 39

Perenyi’s fluid