HT Specimen Handling & Fixation 2

Question 1

Which fixative is MOST appropriate for preserving glycogen in tissue sections?

Accepted Answer

Bouin's fixative

Answer

Bouin's fixative (picric acid, formalin, acetic acid) preserves glycogen well and is commonly used for this purpose.

Question 2

A biopsy specimen arrives in the lab after a 6-hour delay without fixative. What is the MOST likely consequence?

Accepted Answer

Autolytic tissue degradation

Answer

Without fixation, endogenous enzymes continue to digest cellular components, leading to autolysis and loss of tissue architecture.

Question 3

The recommended tissue-to-fixative volume ratio for optimal formalin fixation is:

Accepted Answer

1:10

Answer

A minimum 1:10 tissue-to-formalin ratio ensures adequate fixative penetration and complete fixation.

Question 4

Which of the following BEST describes the mechanism of formalin fixation?

Accepted Answer

Cross-linking of amino groups via methylene bridges

Answer

Formaldehyde reacts with amino groups on proteins to form methylene bridges, creating cross-links that stabilize tissue structure.

Question 5

Which fixative is CONTRAINDICATED when performing acid-fast staining for mycobacteria?

Accepted Answer

Zenker's fixative

Answer

Zenker's fixative contains mercuric chloride, which can interfere with acid-fast staining results and requires extra processing steps.

(HT) Histotechnician Certification Practice Test