1000 Flashcards ASCP Histotechnologist (HTL) Exam
Which fixative is considered the gold standard for 10% neutral buffered formalin (NBF) due to optimal preservation of
routine histology? morphology and compatibility with most stains.
Formalin fixes tissue primarily by forming ______ Methylene bridge cross-links between lysine residues in proteins.
cross-links.
Why is glutaraldehyde preferred over formalin for It provides superior ultrastructural preservation by rapid protein cross-
electron microscopy? linking and minimal extraction artifacts.
A tissue shows excessive shrinkage and poor Inadequate fixation or delayed fixation causing autolysis and
nuclear detail after processing. What is the most enzymatic degradation.
likely cause?
Alcohol is a coagulative fixative that preserves True. Alcohol precipitates proteins and preserves glycogen but causes
glycogen well. tissue shrinkage.
Page 1 of 103
,1000 Flashcards ASCP Histotechnologist (HTL) Exam
Why is osmium tetroxide used in EM fixation? It preserves lipid membranes and enhances electron density for
ultrastructural visualization.
The ideal fixation time for formalin is 6-24 hours depending on tissue type and thickness.
approximately ______ hours per mm of tissue
thickness.
A biopsy is left at room temperature for 12 hours Autolysis causing loss of cellular detail and nuclear fading.
before fixation. What artifact is expected?
What is the key limitation of Bouin's solution? It causes formalin pigment formation and is incompatible with many
immunohistochemical stains.
Why must tissue thickness be controlled during To ensure adequate penetration of fixative and prevent underfixation
fixation? of central tissue areas.
Electron microscopy requires fixation of tissue in Ultrathin (50-100 nm sections).
______-grade sections.
Page 2 of 103
,1000 Flashcards ASCP Histotechnologist (HTL) Exam
What artifact is commonly seen in poorly fixed Cytoplasmic vacuolization due to enzymatic digestion.
liver tissue?
Microwave fixation speeds up protein cross- True. It accelerates fixation but can cause hot spots and artifacts.
linking but may cause uneven fixation.
What is the function of buffer in neutral buffered To maintain pH stability and prevent formalin pigment (acid hematin)
formalin? formation.
A pathologist requests rapid diagnosis Frozen section technique using cryostat for rapid tissue diagnosis.
intraoperatively. Which technique is used?
Frozen sections preserve tissue using ______ rather Physical freezing (cryogenic preservation).
than chemical fixation.
Why are frozen sections less detailed than paraffin Ice crystal formation distorts cellular architecture and reduces
sections? resolution.
What is a major disadvantage of freezing tissue Large ice crystals form, causing severe morphological artifacts.
too slowly?
Acetone is commonly used for fixation in enzyme True, because it preserves enzymatic activity better than formalin.
histochemistry.
Page 3 of 103
, 1000 Flashcards ASCP Histotechnologist (HTL) Exam
What is the principle of light microscopy staining Differential absorption of light due to dyes binding specific cellular
contrast? components.
Hematoxylin stains ______ structures blue-purple. Basophilic structures such as nuclei and ribosomes.
Why is eosin considered an acidic dye? It binds to basic (acidophilic) cytoplasmic proteins.
Tissue shows weak nuclear staining. What is a likely Understaining with hematoxylin or over-differentiation.
technical error?
What is the function of differentiation in H&E To remove excess hematoxylin and improve nuclear clarity.
staining?
Over-fixation can reduce antigen availability in True. Excess cross-linking masks antigenic sites.
immunohistochemistry.
Page 4 of 103
Which fixative is considered the gold standard for 10% neutral buffered formalin (NBF) due to optimal preservation of
routine histology? morphology and compatibility with most stains.
Formalin fixes tissue primarily by forming ______ Methylene bridge cross-links between lysine residues in proteins.
cross-links.
Why is glutaraldehyde preferred over formalin for It provides superior ultrastructural preservation by rapid protein cross-
electron microscopy? linking and minimal extraction artifacts.
A tissue shows excessive shrinkage and poor Inadequate fixation or delayed fixation causing autolysis and
nuclear detail after processing. What is the most enzymatic degradation.
likely cause?
Alcohol is a coagulative fixative that preserves True. Alcohol precipitates proteins and preserves glycogen but causes
glycogen well. tissue shrinkage.
Page 1 of 103
,1000 Flashcards ASCP Histotechnologist (HTL) Exam
Why is osmium tetroxide used in EM fixation? It preserves lipid membranes and enhances electron density for
ultrastructural visualization.
The ideal fixation time for formalin is 6-24 hours depending on tissue type and thickness.
approximately ______ hours per mm of tissue
thickness.
A biopsy is left at room temperature for 12 hours Autolysis causing loss of cellular detail and nuclear fading.
before fixation. What artifact is expected?
What is the key limitation of Bouin's solution? It causes formalin pigment formation and is incompatible with many
immunohistochemical stains.
Why must tissue thickness be controlled during To ensure adequate penetration of fixative and prevent underfixation
fixation? of central tissue areas.
Electron microscopy requires fixation of tissue in Ultrathin (50-100 nm sections).
______-grade sections.
Page 2 of 103
,1000 Flashcards ASCP Histotechnologist (HTL) Exam
What artifact is commonly seen in poorly fixed Cytoplasmic vacuolization due to enzymatic digestion.
liver tissue?
Microwave fixation speeds up protein cross- True. It accelerates fixation but can cause hot spots and artifacts.
linking but may cause uneven fixation.
What is the function of buffer in neutral buffered To maintain pH stability and prevent formalin pigment (acid hematin)
formalin? formation.
A pathologist requests rapid diagnosis Frozen section technique using cryostat for rapid tissue diagnosis.
intraoperatively. Which technique is used?
Frozen sections preserve tissue using ______ rather Physical freezing (cryogenic preservation).
than chemical fixation.
Why are frozen sections less detailed than paraffin Ice crystal formation distorts cellular architecture and reduces
sections? resolution.
What is a major disadvantage of freezing tissue Large ice crystals form, causing severe morphological artifacts.
too slowly?
Acetone is commonly used for fixation in enzyme True, because it preserves enzymatic activity better than formalin.
histochemistry.
Page 3 of 103
, 1000 Flashcards ASCP Histotechnologist (HTL) Exam
What is the principle of light microscopy staining Differential absorption of light due to dyes binding specific cellular
contrast? components.
Hematoxylin stains ______ structures blue-purple. Basophilic structures such as nuclei and ribosomes.
Why is eosin considered an acidic dye? It binds to basic (acidophilic) cytoplasmic proteins.
Tissue shows weak nuclear staining. What is a likely Understaining with hematoxylin or over-differentiation.
technical error?
What is the function of differentiation in H&E To remove excess hematoxylin and improve nuclear clarity.
staining?
Over-fixation can reduce antigen availability in True. Excess cross-linking masks antigenic sites.
immunohistochemistry.
Page 4 of 103
