ASCP Tissue Fixation and Decalcification

Question 1

What is the primary purpose of tissue fixation in histology?

Accepted Answer

To prevent autolysis and putrefaction

Answer

To dehydrate tissue before embedding

Answer

To stain cellular components for visibility

Answer

To harden tissue for paraffin infiltration

Question 2

Which fixative is considered the standard routine fixative used in most histopathology laboratories?

Accepted Answer

10% neutral buffered formalin

Answer

Glutaraldehyde 2.5%

Answer

Carnoy's fixative

Answer

Bouin's solution

Question 3

What is the approximate formaldehyde concentration in a solution labeled '10% neutral buffered formalin'?

Accepted Answer

3.7–4% formaldehyde

Answer

10% formaldehyde

Answer

37–40% formaldehyde

Answer

1% formaldehyde

Question 4

What is the primary chemical mechanism by which formalin fixes tissue?

Accepted Answer

Formation of methylene bridges that cross-link proteins

Answer

Coagulation of proteins through dehydration

Answer

Precipitation of nucleic acids by pH change

Answer

Removal of membrane lipids to expose proteins

Question 5

Bouin's fixative is particularly well-suited for which type of tissue specimen?

Accepted Answer

Testicular and gastrointestinal biopsies

Answer

Bone and calcified specimens

Answer

Tissues for electron microscopy

Answer

Frozen section specimens

Question 6

According to CAP guidelines, what is the recommended fixation time range for standard surgical resection specimens in 10% NBF?

Accepted Answer

6–72 hours

Answer

1–2 hours

Answer

3–5 hours

Answer

1–2 weeks

Question 7

Which fixative is specifically required for optimal ultrastructural preservation in electron microscopy?

Accepted Answer

Glutaraldehyde

Answer

10% neutral buffered formalin

Answer

Zenker's fixative

Answer

Carnoy's fixative