Histology ASCP Exam LATEST VERSION 2026-2027
EXAM WITH ACTUAL TESTBANK 530 QUESTION AND
CORRECT DETAILED ANSWERS WITH RATIONALES.
QUESTION 1
If mercuric chloride is used alone for fixation, it will:
A. Leave tissue proteins uncoagulated
B. Produce a very acidic solution
C. Penetrate poorly and cause excessive shrinkage
D. Decrease tissue affinity for stains
CORRECT ANS: C. Penetrate poorly and cause excessive shrinkage
Expert Rationale
Mercuric chloride is a coagulant fixative that precipitates proteins by forming
complexes with them. When used alone, it penetrates tissue very slowly and
causes significant shrinkage due to its strong protein-precipitating properties. The
poor penetration means that the center of the tissue may remain unfixed, while
the periphery becomes excessively hardened and shrunken. This is why mercury-
containing fixatives like Zenker's and B-5 solutions are typically combined with
other fixatives such as acetic acid (to reduce shrinkage) and formaldehyde (to
improve penetration). Mercuric chloride does not leave proteins uncoagulated (A);
it actively coagulates them. It does not produce a very acidic solution (B) when
used alone. It does not decrease tissue affinity for stains (D); in fact, mercury-
containing fixatives often enhance nuclear staining.
,DIF: Cognitive Level: Understand (Comprehension)
TOP: Fixation - Mercuric Chloride
MSC: Histology ASCP Exam
QUESTION 2
Carnoy solution is recommended for the preservation of:
A. Acid-fast bacilli
B. Nucleic acids
C. Lipids
D. Red blood cells
CORRECT ANS: B. Nucleic acids
Expert Rationale
Carnoy's fixative is a rapid-acting, non-additive fixative composed of absolute
alcohol, chloroform, and glacial acetic acid. It is particularly recommended for the
preservation of nucleic acids because it rapidly penetrates tissues and precipitates
DNA and RNA while minimizing hydrolysis. The combination of alcohol and acetic
acid in Carnoy's solution helps to preserve nuclear detail and is often used for
cytogenetic studies and for the Feulgen reaction, which specifically demonstrates
DNA. It is not recommended for acid-fast bacilli (A), which require specific fixation
for lipid preservation. Carnoy's solution dissolves lipids (C) and lyses red blood
cells (D) due to the presence of acetic acid and alcohol.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Fixation - Carnoy Solution
MSC: Histology ASCP Exam
,QUESTION 3
Which factor effects light microscopy the least?
A. Temperature
B. Volume ratio
C. Penetration rate
D. pH
CORRECT ANS: D. pH
Expert Rationale
While pH is important in certain histological applications, it has the least direct
effect on light microscopy compared to the other factors listed. Temperature (A)
affects the rate of fixation, staining, and enzymatic reactions, and can also
influence the viscosity of reagents. Volume ratio (B) is critical for fixation and
processing; an inadequate volume of fixative relative to tissue can lead to poor
fixation. Penetration rate (C) is a key property of fixatives and processing reagents,
affecting how quickly and uniformly the tissue is fixed and processed. pH, while
crucial for specific staining reactions (e.g., Alcian Blue) and for maintaining
ultrastructural detail in electron microscopy, has the least overall impact on the
basic optics and performance of light microscopy. The resolution and contrast in
light microscopy are primarily determined by the wavelength of light and the
numerical aperture of the objective lens.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Light Microscopy - Factors
MSC: Histology ASCP Exam
, QUESTION 4
Formalin pigment is generally created in tissues fixed in formalin when the pH:
A. Rises above 6
B. Falls below 6
C. Is buffered to neutrality
D. Is 7.2
CORRECT ANS: B. Falls below 6
Expert Rationale
Formalin pigment, also known as acid formaldehyde hematin, is a brown-black,
crystalline artifact that forms in tissues fixed in formalin when the pH of the
fixative falls below 6.0. This occurs when formalin is improperly buffered or when
it is exposed to acidic conditions, such as the presence of formic acid (which
forms from the oxidation of formaldehyde). The pigment is deposited in tissues,
particularly in areas rich in blood, and can obscure cellular detail. The formation of
formalin pigment can be prevented by buffering formalin to a neutral pH (around
7.0-7.4) using phosphate buffers or by using calcium carbonate to neutralize the
acidity. When the pH rises above 6 (A), is buffered to neutrality (C), or is at 7.2 (D),
pigment formation is typically prevented.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Fixation - Formalin Pigment
MSC: Histology ASCP Exam
QUESTION 5
Very bloody cytology smears are often treated with:
EXAM WITH ACTUAL TESTBANK 530 QUESTION AND
CORRECT DETAILED ANSWERS WITH RATIONALES.
QUESTION 1
If mercuric chloride is used alone for fixation, it will:
A. Leave tissue proteins uncoagulated
B. Produce a very acidic solution
C. Penetrate poorly and cause excessive shrinkage
D. Decrease tissue affinity for stains
CORRECT ANS: C. Penetrate poorly and cause excessive shrinkage
Expert Rationale
Mercuric chloride is a coagulant fixative that precipitates proteins by forming
complexes with them. When used alone, it penetrates tissue very slowly and
causes significant shrinkage due to its strong protein-precipitating properties. The
poor penetration means that the center of the tissue may remain unfixed, while
the periphery becomes excessively hardened and shrunken. This is why mercury-
containing fixatives like Zenker's and B-5 solutions are typically combined with
other fixatives such as acetic acid (to reduce shrinkage) and formaldehyde (to
improve penetration). Mercuric chloride does not leave proteins uncoagulated (A);
it actively coagulates them. It does not produce a very acidic solution (B) when
used alone. It does not decrease tissue affinity for stains (D); in fact, mercury-
containing fixatives often enhance nuclear staining.
,DIF: Cognitive Level: Understand (Comprehension)
TOP: Fixation - Mercuric Chloride
MSC: Histology ASCP Exam
QUESTION 2
Carnoy solution is recommended for the preservation of:
A. Acid-fast bacilli
B. Nucleic acids
C. Lipids
D. Red blood cells
CORRECT ANS: B. Nucleic acids
Expert Rationale
Carnoy's fixative is a rapid-acting, non-additive fixative composed of absolute
alcohol, chloroform, and glacial acetic acid. It is particularly recommended for the
preservation of nucleic acids because it rapidly penetrates tissues and precipitates
DNA and RNA while minimizing hydrolysis. The combination of alcohol and acetic
acid in Carnoy's solution helps to preserve nuclear detail and is often used for
cytogenetic studies and for the Feulgen reaction, which specifically demonstrates
DNA. It is not recommended for acid-fast bacilli (A), which require specific fixation
for lipid preservation. Carnoy's solution dissolves lipids (C) and lyses red blood
cells (D) due to the presence of acetic acid and alcohol.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Fixation - Carnoy Solution
MSC: Histology ASCP Exam
,QUESTION 3
Which factor effects light microscopy the least?
A. Temperature
B. Volume ratio
C. Penetration rate
D. pH
CORRECT ANS: D. pH
Expert Rationale
While pH is important in certain histological applications, it has the least direct
effect on light microscopy compared to the other factors listed. Temperature (A)
affects the rate of fixation, staining, and enzymatic reactions, and can also
influence the viscosity of reagents. Volume ratio (B) is critical for fixation and
processing; an inadequate volume of fixative relative to tissue can lead to poor
fixation. Penetration rate (C) is a key property of fixatives and processing reagents,
affecting how quickly and uniformly the tissue is fixed and processed. pH, while
crucial for specific staining reactions (e.g., Alcian Blue) and for maintaining
ultrastructural detail in electron microscopy, has the least overall impact on the
basic optics and performance of light microscopy. The resolution and contrast in
light microscopy are primarily determined by the wavelength of light and the
numerical aperture of the objective lens.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Light Microscopy - Factors
MSC: Histology ASCP Exam
, QUESTION 4
Formalin pigment is generally created in tissues fixed in formalin when the pH:
A. Rises above 6
B. Falls below 6
C. Is buffered to neutrality
D. Is 7.2
CORRECT ANS: B. Falls below 6
Expert Rationale
Formalin pigment, also known as acid formaldehyde hematin, is a brown-black,
crystalline artifact that forms in tissues fixed in formalin when the pH of the
fixative falls below 6.0. This occurs when formalin is improperly buffered or when
it is exposed to acidic conditions, such as the presence of formic acid (which
forms from the oxidation of formaldehyde). The pigment is deposited in tissues,
particularly in areas rich in blood, and can obscure cellular detail. The formation of
formalin pigment can be prevented by buffering formalin to a neutral pH (around
7.0-7.4) using phosphate buffers or by using calcium carbonate to neutralize the
acidity. When the pH rises above 6 (A), is buffered to neutrality (C), or is at 7.2 (D),
pigment formation is typically prevented.
DIF: Cognitive Level: Understand (Comprehension)
TOP: Fixation - Formalin Pigment
MSC: Histology ASCP Exam
QUESTION 5
Very bloody cytology smears are often treated with:
