PRELIM: CH4 Conventional Tissue Processing (2)

3–5 μm

During routine microtomy, tissue sections for Hematoxylin and Eosin (H&E) staining are generally cut at what thickness?

8–12 μm

A pathologist suspects amyloidosis in a liver biopsy. To optimize visualization of amyloid deposits, the tissue should be sectioned at approximately:

2 μm

Kidney biopsies are routinely sectioned at approximately ______ to provide optimal visualization of the glomeruli.

It does not provide a sufficiently hard supporting matrix.

Why is paraffin wax NOT suitable for ultrathin sections required in Electron Microscopy (EM)?

Epoxy resin

Which embedding medium is MOST commonly used for semi-thin and ultrathin sections in Electron Microscopy?

Immunohistochemistry (IHC)

Acrylic resins are particularly useful when which laboratory technique will be performed?

Glass or diamond knives

Plastic blocks composed of methacrylate, Araldite, or Epon are sectioned using:

Diamond knife

Which knife provides the BEST performance for ultrathin sections (approximately 0.25 μm) intended for Electron Microscopy?

To improve adhesion of the tissue section to the glass slide

Why are freshly cut paraffin sections commonly placed in a warm oven for about 15 minutes?

Use glue-coated slides instead of heating

If heating could damage tissue antigens needed for Immunohistochemistry (IHC), what alternative should be used?

• Tearing

• Folding

• Creases

Which of the following are likely to be considered a sectioning artifact?

To remove wrinkles and flatten the section

What is the primary purpose of floating paraffin sections on a warm water bath before mounting?

5–10°C below the melting point of the embedding wax

The temperature of the flotation water bath should generally be maintained:

Desiccated (dried-out) appearing tissue sections

If the flotation bath temperature is TOO HIGH, which artifact is MOST likely to occur?

Excessive wrinkling

If the flotation bath temperature is TOO LOW, the tissue section will most likely exhibit:

Overhydration may occur, producing an appearance similar to edema microscopically

Why should tissue ribbons NOT remain in the flotation bath for more than 1–2 minutes?

A few drops of ethyl alcohol

Which substance may be added to the flotation bath to facilitate mounting of tissue sections?

Albumin or poly-L-lysine

Because tissue sections do not adhere well to untreated glass slides, which bonding agent is commonly added to the flotation water bath?

Floater

A histotechnologist notices a tiny fragment of unrelated tissue on a patient's slide after mounting. This artifact is known as a:

They may lead to an incorrect diagnosis if unrelated tissue is mistaken as part of the patient's specimen.

Why are "floaters" considered one of the most serious problems in histotechnology?

A cancerous tissue fragment from one patient contaminates another patient's benign biopsy slide.

Which situation BEST illustrates the potential danger of a floater?

Frequently skim or replace the water and clean the water bath between cases.

What is the BEST way to minimize floaters in the flotation water bath?

Tissue remaining on a wooden tongue depressor that is subsequently used for another case.

"Tongue blade metastasis" refers to contamination caused by:

To allow additional sections (remounts) to be prepared without recutting the tissue block if requested.

Why is it advisable to save unmounted paraffin ribbons from small biopsies for at least one week?

Xylene

Before staining, paraffin sections must first be deparaffinized. Which reagent is primarily responsible for removing paraffin?

Absolute alcohol

After xylene removes paraffin from tissue sections, which reagent removes the xylene before rehydration?

Dyes bind selectively to specific cellular and extracellular components to create microscopic contrast.

Which statement BEST describes routine histologic staining?

Deparaffinized tissue fragments may break free into shared staining solutions and contaminate other slides.

Why is contamination during staining often more likely than contamination during flotation?

Frequently changing the xylene and alcohol baths, particularly the first solutions used

Which practice helps reduce contamination originating from staining baths?

Automatic tissue processors improve efficiency by moving tissues through programmed reagent sequences.

Which statement correctly compares manual tissue processing with automatic tissue processing?

Carousel processor

In older automatic tissue processors, tissues are placed in a cage that moves through a series of reagent containers. This design is known as a:

Hold tissues in a chamber while reagents are pumped in and out automatically.

Modern tissue processors differ from carousel processors because they primarily:

It improves wax penetration, helps remove trapped air, and reduces exposure to prolonged heat.

What is the primary advantage of vacuum infiltration during tissue processing?

Low reagent temperature that increases viscosity

Which factor would MOST SLOW tissue processing by reducing reagent diffusion?

Reduced fluid exchange resulting in incomplete processing and infiltration

A histotechnologist tightly packs numerous tissue specimens into one cassette before processing. What is the MOST likely consequence?