Unit 6 Decalcification

1. A bone section is cutting poorly during microtomy because calcium remains in the tissue. What corrective step should the histotechnologist take to salvage the block?

d. Apply surface acid treatment to the exposed block face

2. Which element is the primary target of acid-based decalcification procedures?

b. Calcium

3. When tissue is left in acid for too long during decalcification, which cellular component will show the most deterioration under the microscope?

a. Nuclei

4. To ensure consistent and efficient decalcification, the decalcifying fluid should be used in what proportion relative to tissue volume?

b. 20 parts fluid : 1 part tissue

5. A histotech needs to determine the completion of decalcification in bone tissue fixed in B- Which test would yield the most reliable results?

b. Calcium oxalate chemical test

6. Decalcification should begin immediately after the tissue is removed from the patient.

false

7. How does gentle agitation during decalcification influence the process?

a. It speeds calcium removal by refreshing solution contact

8. Following complete decalcification, a bone sample fails to demonstrate calcium with a von Kossa stain. What should the technologist conclude?

d. Accept the result; absence of calcium means successful decalcification

9. Which combination correctly identifies acid-based methods for removing calcium?

d. a and c (5% hydrochloric acid, Electrolytic method)

10. Which of the following is a chelating compound that binds calcium ions rather than dissolving them?

c. Ethylenediamine tetraacetic acid (EDTA)

11. Bouin solution is an appropriate fixative when a breast biopsy requires evaluation for microcalcifications.

b. False

12. When embedding bone, orienting the long axis horizontally to the microtome blade provides the best cutting surface.

b. False

13. Which weak acid is most commonly employed for routine decalcification of bone and teeth?

a. Formic acid

14. Which of the following actions would help accelerate the decalcification process without severely damaging tissue?

c. Increasing agitation to promote ion exchange

15. Which of the following is not considered an acid decalcification method?

c. Chelation method

16. Which strong inorganic acid is sometimes used when rapid decalcification is necessary?

d. Nitric acid

17. During the chemical test for end-point decalcification, which substance confirms the presence of remaining calcium by forming a white precipitate?

d. Calcium oxalate

18. Which acid is least likely to damage nuclear basophilia during decalcification?

d. Formic acid

19. When bone fixed in Helly’s solution undergoes decalcification, which end-point test offers the most accurate results?

d. Radiographic method

20. Raising the temperature of a decalcifying solution will:

a. Increase the reaction rate but may compromise staining

21. A specimen decalcified in hydrochloric acid shows faint nuclear staining with hematoxylin. Which is the most probable cause?

d. Excessive exposure to acid

22. Ion exchange resin facilitates which type of decalcification process?

a. Acid-based

23. For formalin-fixed bone tissue, which method provides the most precise assessment of complete decalcification?

d. Using radiography

24. Chelating agents used for decalcification work by:

a. Binding metal ions to form soluble complexes

25. Which statement correctly describes the electrolytic method of decalcification?

a. Calcium migrates toward the cathode under an electrical current

26. Why is it important to determine the optimal end point in decalcification?

a. To minimize tissue distortion and prevent overexposure to acid

27. The radiographic method for end-point testing provides which advantage over other methods?

a. Fast and highly accurate visualization of residual calcium

28. Which statement correctly describes a disadvantage of the mechanical (flexibility) test for endpoint decalcification?

a. It can damage tissue structure and introduce artifacts

29. Surface decalcification is best described as:

a. Applying acid to the exposed face of a tissue block to remove residual calcium

30. When is surface decalcification not recommended?

b. When processing breast biopsies containing microcalcifications

31. Which of the following factors would slow the decalcification process?

a. Low temperature

32. Why is the von Kossa stain inappropriate for tissue that has already undergone decalcification?

a. The calcium has been removed, leaving nothing for silver to react with

For optimal processing bone tissue should not exceed

4-5 mm

What are the two basic methods of decalcification?

acid; chelating

T/F ion-exchange resins is an acid method

true

T/F ion-exchange resins is a chelating method

false

Which is the superior method of decalcification?

ion-exchange resins

____ ions from a resin are exchanged for calcium ions

ammonium

Electrolytic method has which two acids in solution

formic; HCl

Electrolytic method reaction generates __

heat

What are chelating agents?

organic compounds that combines with a metal ion to form a metal chelate

What are the different tests for optimal decalcification?

• mechanical or physical

• chemical

• radiographic

• weight loss, weight gain

What detects calcium in chemical test for endpoint?

calcium oxalate

White precipitate indicates the …

presence of calcium oxalate

What is the most accurate method of testing endpoint?

radiography

What type of fixatives cannot be used with radiography?

metallic fixatives

Why does weight gain happen with the weight loss, weight gain method?

once calcium is totally removed, water replaces the calcium and weight begins to go up

After decalcification, tissue can be neutralized with..

lithium carbonate, sodium bicarbonate

T/F underdecalcified bone is basophilic

true

T/F overdecalcified bone is basophilic

false

Overdecalcified bone shows up as

damaged and poor staining