Introduction to Histology and Cytology - Flashcards (60)

60 practice flashcards covering the key concepts from the MLHG 106 Introduction to Histology and Cytology lecture notes.

What is Anatomic Pathology?

The study of disease through tissue or cellular samples; includes cytopathology and histopathology.

What is Cytopathology?

Diagnosis based on the characteristics of cells in cytology samples.

What is Histopathology?

Examination of tissue pieces under the microscope to study disease.

What is the role of the histotechnologist?

Prepares specimens for the pathologist, including accessioning, staining, cover slipping, and filing.

What does accessioning involve?

Receiving specimens, assigning a unique accession number, and logging in the daily accession log.

What is specimen rejection?

Laboratory protocol for rejecting specimens due to labeling errors, missing or incorrect requisitions, wrong fixative, inadequate fixative, leaks, or improper containers.

Why is PPE important in the histology lab?

To protect workers and reduce exposure to hazards; PPE is selected based on tasks and hazards.

What is WHMIS?

Workplace Hazardous Materials Information System; governs labeling, SDS, storage and disposal of hazardous materials.

What is spill containment?

Procedures to contain and clean up spills of biological or hazardous materials.

How should sharps be handled in histology labs?

Handled and disposed of in designated sharps containers with proper safety procedures.

What is the foundation of both cytology and histology labs?

Assessment of morphologic features of cells and tissues.

What is the goal of staining in histology?

Highlight cell morphology to assist in diagnosis and tissue identification.

What is the typical lab workflow for a surgical specimen?

Receive, fix, process, embed, section, stained, and examined by pathologist.

Who prepares samples for the pathologist to examine?

Histotechnologists.

What types of specimens are processed in histology?

Surgical specimens, autopsy specimens, and various biopsies.

What does FFPE stand for?

Formalin-Fixed Paraffin-Embedded.

What is FFPE in practice?

Tissue is fixed in formalin, then embedded in paraffin for sectioning.

What is H&E staining?

Hematoxylin and eosin stain; nuclei stain blue/purple, cytoplasm stains pink.

What is a tissue block in histology?

A paraffin-embedded block containing the processed tissue used for sectioning.

What is a tissue cassette?

Plastic container that holds tissue pieces during processing and embedding.

What is a rotary microtome used for?

To cut thin paraffin sections from FFPE blocks for mounting on slides.

What thickness are standard histology sections?

Typically 3–5 microns.

What is the purpose of paraffin embedding?

To provide support for tissue so thin sections can be cut without distortion.

What is fixation in histology?

The process that preserves tissue structure and halts autolysis and putrefaction.

What is ischemic time?

The time from tissue removal from the body until placement in fixative.

What fixative volume is recommended relative to tissue?

Fixative volume should be 15–20 times the tissue volume.

What is the fixation rate?

Tissue is fixed at about 1 mm penetration per hour.

What are the main fixation methods?

Chemical fixation (immersion or perfusion) and physical methods (heat, microwaving, cryopreservation).

What pH is preferred for fixatives used in electron microscopy?

Buffered to pH 7.2–7.4.

Why does tissue size matter in fixation?

Larger or denser tissues fix more slowly due to slower fixative penetration.

What is the primary goal of fixation?

Stabilize proteins and preserve tissue structure for downstream processing.

What is additive vs non-additive fixative?

Additive fixatives actively participate in denaturing proteins; non-additive fixatives do not.

What is coagulant vs non-coagulant fixative?

Coagulant fixatives cause heavy precipitates and more shrinkage; non-coagulant cause lighter precipitates with less shrinkage.

Name some primary fixing agents.

Formaldehyde, potassium dichromate, mercuric chloride, ethanol, picric acid, acetic acid, osmium tetroxide, glutaraldehyde.

What is Zenker's fluid?

Fixative containing mercuric chloride; good staining but highly toxic and corrosive to metal.

What is Bouin's fluid?

Fixative containing picric acid; good glycogen demonstration; rapid penetration but tissues become hard and Picric acid is explosive.

What is Brasil's alcoholic picro-formal fixative?

Fixative used routinely for glycogen demonstration; shares disadvantages of picric-containing fixatives.

What should you know about common histology reagents storage?

Store in airtight bottles in a cool, dark place; handle toxic components with SDS guidance.

What is specimen receiving and accessioning?

Specimens arrive with requisition; labelled; surgical number assigned; logged in an accession log.

What is a surgical number?

A unique identifier assigned to a specimen and used on requisitions, containers, cassettes and slides.

What information is on a requisition?

Patient name, date, tissue type, site, physician, patient location.

What is specimen rejection policy?

Written policy addressing who can submit, minimum volumes, container suitability, requisition completeness.

What are the priority specimen levels and their TATs?

Emergency Department NOW; STAT 1 hour; ASAP 4 hours; Routine 24 hours.

How should fresh specimens be transported?

Delivered to the lab without delay; keep refrigerated if possible and avoid freezing; fixed specimens are less critical.

What is TDG packaging for biological materials?

Rigid leak-proof container; absorbent material; leak-proof secondary container; outer container.

How should dry ice be packaged?

Do not seal dry ice in the secondary container; place between the plastic container and outer bag.

What is specimen labeling important for safety and traceability?

Ensures traceability from requisition to cassettes to slides and final report.

What are fixation artifacts?

Unwanted changes from improper fixation, such as pigment formation or uneven staining.

What is formalin pigment and how is it removed?

Acid hematin pigment formed by acidic formalin; removed with alcoholic picric acid or alkaline alcohol.

What is paraformaldehyde in fixatives and how is it managed?

Formaldehyde polymer; removed by filtration; methanol may be added in commercial fixatives to prevent polymerization.

What are the dangers of formaldehyde/formalin?

Irritating vapors; potential dermatitis; carcinogenic; use fume hood and proper PPE.

What is the universal histology fixative?

10% neutral buffered formalin (NBF).

What is the composition of 10% neutral buffered formalin (approximate)?

Formalin solution around 3.7–4% formaldehyde buffered to neutral pH.

What are the advantages of using formalin as a fixative?

Good penetration; universal fixative; inexpensive; useful for nervous system; blocks don’t require washing.

What are the disadvantages of using formalin?

Vapors irritate mucous membranes; carcinogenic; can cause dermatitis; not ideal for electron microscopy.

What is the difference between fixed and unfixed specimens?

Fixed specimens have been preserved; unfixed require prompt fixation or rapid processing.

What is the purpose of embedding in paraffin?

To support tissue so it can be thinly sectioned without damage.

What is sectioning temperature during microtomy?

Paraffin blocks are cut at 58–60°C to produce thin sections.

What is the role of slide mounting and staining?

Mounting places the section on a slide for viewing; staining (e.g., H&E) highlights structures.

What is IHC-grade paraffin block used for?

Paraffin block prepared for immunohistochemistry staining.

What is the purpose of fixation rate and penetration?

To ensure timely and uniform fixation across tissue for accurate morphology.

What is a microtome used for?

Cutting thin sections from paraffin-embedded tissue for mounting on slides.

What is an autopsy specimen?

Tissue obtained during autopsy to determine cause of death or for research and teaching.

What is a surgical specimen?

Tissue obtained from surgery or biopsy intended for diagnostic evaluation.

What is the function of a requisition form?

Provide essential patient and specimen information to accompany the sample.

What is meant by “tissue processing” steps?

Fixation, dehydration, clearing, infiltration, embedding, trimming, sectioning, staining.

What is the consequence of uneven fixation (zonal fixation)?

Uneven staining and morphology across the tissue.

What is a safety incident documentation importance?

Recording incidents supports safety improvements and accountability.

What does microwave fixation refer to?

A physical fixation method using microwave energy to speed fixation.

What is the purpose of pH control in fixation for EM?

Maintains ultrastructural preservation; typically pH 7.2–7.4.

What is the role of fixative choice in tissue demonstration?

Different fixatives preserve different structures and affect downstream staining.

What is the fixative volume rule (15–20x) used for?

Ensures adequate penetration and preservation of the tissue.

What is the practical effect of increased fixation temperature?

Often speeds fixation but must balance tissue morphology.

What is the meaning of TAT?

Turn Around Time – time from receipt of a specimen to release of results.

What is the importance of a daily accession log?

Keeps track of all specimens from receipt to reporting.

Why is refrigeration recommended for non-fixed specimens on arrival?

To slow decomposition and preserve tissue until proper fixation.

What is the importance of labeling accuracy?

Prevents misidentification and errors in diagnosis.

What is the role of spillage and hazard response in histology?

Ensure quick containment and proper cleanup to prevent exposure.

What is a clear fixative's primary action on proteins?

Denatures and stabilizes proteins for subsequent processing.

What is an example of an additive fixative?

Formaldehyde is often considered additive and fixative.

What is a non-additive fixative example?

Mercuric chloride can act as a non-additive fixative depending on context.

What is a coagulant fixative's effect on tissue?

Causes heavy protein precipitates and tissue shrinkage.

What is a non-coagulant fixative's effect on tissue?

Forms a lighter precipitate with less shrinkage.

What type of fixative is osmium tetroxide used for?

A primary fixing agent used especially in electron microscopy to preserve lipids.

What is the main purpose of the requisition in histology?

To provide essential clinical and specimen information for processing and diagnosis.

What should you check before processing fixed specimens?

Ensure fixation is complete and adequate for consistent downstream processing.