L2 CONVENTIONAL TISSUE PROCESSING

b

What is the primary purpose of the "Fixation" step in tissue processing?

a) To remove calcium deposits from the tissue

b) To preserve tissue structure and harden it

c) To dissolve lipids and fats

d) To cut the tissue into thin sections

a

Which chemical is cited as the most popular fixative, commonly used as a phosphate-buffered solution?

a) Formaldehyde solution/formalin

b) Xylene

c) Trichloroethane

d) Absolute ethanol

d

How long can formalin-fixed, paraffin-embedded tissues be safely stored at room temperature?

a) Up to 48 hours

b) One to two weeks

c) Six months maximum

d) Indefinitely

c

Which step is designated as an optional process meant specifically to remove calcium deposits from specimens like bone?

a) Impregnation

b) Clearing

c) Decalcification

d) Dehydration

a

What is the primary purpose of immersing specimens in a series of ethanol solutions during "Dehydration"?

a) To remove water from specimens before infiltration with hydrophobic paraffin wax

b) To impart optical clarity to the tissue

c) To permanently stain the cellular components

d) To recover nucleic acids like DNA and RNA

b

When dehydrating fatty tissues such as breast or lipoma, which superior fat solvents are recommended before the final absolute ethanol step?

a) Xylene and toluene

b) Acetone and isopropanol

c) Formalin and saline

d) Agar and nitrocellulose

c

What is the specific role of a "Clearing" agent in the tissue processing sequence?

a) It bonds the tissue section to the glass slide

b) It hydrates the tissue for water-soluble dyes

c) It removes a substantial amount of fat and transfers the tissue to a solvent miscible with both ethanol and wax

d) It completely dissolves the embedded wax matrix

b

Why is the term "Clearing" used for this specific intermediate step?

a) It cleans the tissue of all microscopic debris

b) The agents impart optical clarity or transparency to the tissue due to their high refractive index

c) It flushes out the fixative chemicals from the specimen

d) It renders the tissue completely white

c

Which specific chemical agent is commonly used in the clearing sequence, typically requiring multiple 20 to 45-minute immersions?

a) Acetone

b) Ethanol

c) Xylene

d) Formalin

c

What is the process of infiltrating cleared tissue with a suitable histological wax called?

a) Dehydration

b) Sectioning

c) Impregnation

d) Mounting

d

At what approximate temperature is paraffin wax kept liquid to allow for proper tissue infiltration?

a) 20 C

b) 37 C

c) 45 C

d) 60 C

a

To improve the properties of purified paraffin wax during embedding, which of the following additives are frequently mixed in?

a) Resins like styrene or polyethylene

b) Albumin and poly-L-lysine

c) Epoxy and acrylic

d) Xylene and ethanol

b

What is the main objective of the "Embedding" process?

a) To completely remove all remaining water from the cells

b) To orient processed tissue into a paraffin block for sectioning

c) To introduce dyes into the specific cell components

d) To place a coverslip over the tissue on a slide

b

What technique is considered highly reliable for handling minute and friable tissue fragments, utilizing a supporting medium like agar before wax infiltration?

a) Vacuum infiltration

b) Double embedding

c) Endoscopic mounting

d) Cold plate freezing

a

What specialized device is used to cut the embedded tissues into very thin sections?

a) Microtome

b) Centrifuge

c) Scalpel array

d) Cryostat

c

What is the standard section thickness required for routine Hematoxylin and Eosin (H&E) staining?

a) 0.25 um

b) 2 um

c) 3-5 um

d) 8-10 um

d

If a histopathologist needs to evaluate amyloid deposits, what section thickness is explicitly required?

a) 0.35 um

b) 2 um

c) 3-5 um

d) 8-10 um

b

Paraffin is not suitable for electron microscopy. Which type of resin must be used instead to achieve thin sections?

a) Styrene resin

b) Epoxy or acrylic resins

c) Poly-L-lysine resin

d) Nitrocellulose resin

c

Immediately after cutting, why are tissue sections floated on a warm water bath?

a) To dissolve the excess paraffin wax

b) To wash away the clearing agents

c) To remove wrinkles from the sections

d) To stain the tissues with a base dye

b

What is the purpose of placing glass slides with newly mounted specimens in a warm oven at 60 C?

a) To rapidly rehydrate the cells

b) To dry the slides and melt the wax to improve adhesion

c) To complete the decalcification process

d) To neutralize the fixative solution

c

During the chemical reagent phase of staining, what is the role of absolute alcohol?

a) It removes the paraffin

b) It binds the dye to the cell nucleus

c) It removes the xylene

d) It floats the tissue onto the slide

b

What term is used to describe friable small tissue fragments that float on the water surface and may be picked up inadvertently, risking diagnostic errors?

a) Artifacts

b) Floaters

c) Creases

d) Resins

b

Which of the following substances are cited as suitable bonding agents to ensure tissue sections adhere properly to glass slides?

a) Formalin and xylene

b) Albumin and poly-L-lysine

c) Epoxy and agar

d) Styrene and polyethylene

c

Correct Answer: b

What is the optimal temperature setting for the warm water bath used in microtomy?

a) Exactly at the melting point of the wax

b) 5-10 C above the melting point of the wax

c) 5-10 C below the melting point of the embedding wax

d) Constant 60 C

c

What happens to tissue sections if the water bath during microtomy is too hot?

a) Excessive wrinkling of the tissue

b) Rehydration of the specimen

c) The creation of desiccated-looking sections

d) The tissues become totally transparent

b

Which laboratory practice is specifically warned against to prevent "tongue blade metastasis" (cross-contamination) during sectioning?

a) Adding ethyl alcohol to the water bath

b) Using the same wooden applicator stick for different cases

c) Skimming the water bath surface between cases

d) Leaving the ribbon in the bath for more than 2 minutes

c

How does the application of vacuum infiltration benefit the automatic tissue processing cycle?

a) It removes all the nucleic acids from the tissue

b) It cools the wax to solidify it faster

c) It assists complete and rapid impregnation while minimizing heat-induced tissue hardening

d) It replaces the need for clearing agents entirely

b

According to the factors impacting processing duration, why is continuous agitation desirable?

a) It permanently sets the tissue orientation in the block

b) It increases the flow of fresh fluids around the tissues, increasing diffusion

c) It mechanically cuts the tissue into smaller fragments

d) It generates heat that replaces the need for a warm water bath

c

What negative impact occurs if the processing temperatures are too high?

a) Increased reagent viscosity reducing diffusion rate

b) Tissues become spongy and retain too much water

c) Tissue shrinkage, hardening, and brittleness

d) Excessive optical clarity obscuring the cells

c

In terms of tissue density and thickness impacting infiltration, which type of tissue is noted to infiltrate more rapidly than dense tissues?

a) Bone

b) Cartilage

c) Spongy tissues (e.g., lungs)

d) Fatty tissues (e.g., breast)