PRELIM: CH8 Decal

To remove calcium ions so the tissue becomes soft enough to section

What is the primary purpose of decalcification in histologic processing?

Bone

Which specimen is most commonly subjected to decalcification in a surgical pathology laboratory?

Teeth

Which of the following specimens may also require decalcification?

Mineralized bone is too hard to cut normally with a microtome

Why is decalcification necessary before routine paraffin sectioning of bone?

Surface decalcification

A pathologist suspects that a bone specimen contains extensive calcification that was not anticipated during processing. What technique may be used after the tissue has already been embedded in paraffin?

Calcium removal may require days or weeks depending on specimen size and density

Why is decalcification generally considered a lengthy procedure?

Low-speed saw

A laboratory wants to reduce an undecalcified bone specimen to approximately 2–3 mm while preserving tissue integrity. Which instrument is most appropriate?

It can cause mechanical damage and force bone fragments into soft tissue

Why can a coarse saw be problematic when preparing bone specimens?

A metabolic bone disease study requiring differentiation between mineralized bone and osteoid

Which situation would favor preparation of undecalcified bone rather than decalcified bone?

It allows mineralized bone to be distinguished from osteoid

What is one major advantage of retaining mineral content when studying metabolic bone disease?

Sawing into thin wafers followed by grinding with abrasive surfaces

Which technique may be used to prepare sections of mineralized, undecalcified bone?

Acid dissolution and chelation

Which pair correctly represents the two major mechanisms used in decalcification?

They form soluble calcium salts through ion exchange

How do mineral acids primarily remove calcium from bone?

By chelating and sequestering calcium ions

How does EDTA primarily remove calcium?

Ethylene diamine tetraacetic acid

EDTA stands for:

EDTA (ethylenediaminetetraacetic acid)

Which decalcifying agent is preferred when preservation of DNA and other molecular components is especially important?

Fixation protects cellular and fibrous elements from damage caused by decalcifying agents

Why should bone specimens generally be adequately fixed before decalcification?

It may become macerated and stain poorly

What may happen when a poorly fixed specimen is placed into a decalcifying solution?

Bone marrow

Which tissue component is particularly vulnerable to poor fixation during bone decalcification?

Fixation → decalcification → impregnation

What is the recommended sequence for bone processing?

To improve penetration of the fixative and facilitate adequate fixation

Why should large bone specimens be sawn into thin slices soon after collection?

Cartilage generally does not require softening unless calcified areas are present

Which statement about cartilage is correct?

Toenails are composed mainly of insoluble keratin filaments

Why is placing a toenail in decalcifying solution considered inappropriate?

Strong mineral acids, weak organic acids, and chelating agents

Which three categories represent the major types of decalcifying agents?

Damage to nuclear and cytoplasmic detail

What is a major disadvantage of prolonged exposure to acidic decalcifying agents?