HT Tissue Processing 2

Question 1

Which dehydrating agent is considered most miscible with both water and paraffin, making it a common transitional fluid in processing?

Accepted Answer

Dioxane

Answer

Dioxane is miscible with both water and paraffin wax, allowing it to serve as both dehydrant and clearing agent in a single step.

Question 2

What is the primary purpose of the clearing step in tissue processing?

Accepted Answer

To replace dehydrant with a paraffin-miscible fluid

Answer

Clearing replaces the dehydrating agent with a substance miscible with paraffin wax, preparing tissue for infiltration.

Question 3

Over-dehydration of tissue in concentrated alcohol most commonly results in which artifact?

Accepted Answer

Tissue shrinkage and hardening

Answer

Prolonged exposure to high-concentration alcohols extracts water excessively, causing tissue to shrink and become brittle.

Question 4

Which vacuum level is most commonly used during automated vacuum-assisted tissue processing to improve reagent penetration?

Accepted Answer

250 mmHg

Answer

Approximately 250 mmHg (one-third atmosphere) is routinely used; deeper vacuum can cause tissue damage while shallower vacuum reduces benefit.

Question 5

A histotechnician notices that bone biopsy cores remain gritty after standard paraffin processing. The most likely cause is:

Accepted Answer

Inadequate decalcification before processing

Answer

Residual mineral calcium salts cause hardness; bone must be fully decalcified before routine paraffin processing to allow sectioning.

(HT) Histotechnician Certification Practice Test