Histological Staining Principles Lecture 4 Quiz

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33 Questions

Why do we need to stain tissue sections?

To obtain useful clinical information

Which type of staining is used to selectively demonstrate tissue elements within tissue sections for research purposes?

Special Stains

What happens to tissue sections when they are prepared without staining?

They remain transparent

What is the main purpose of immunohistochemistry?

To demonstrate tissue elements selectively

Which method of staining is used to visualize specific proteins or antigens in tissue sections?

Immunohistochemistry

What is the purpose of vital stains in histology?

To examine living cells or tissues

What is the main component of cells, making up 80% of their composition?

Water

What type of epithelium is characterized by a single layer of tall, narrow cells with their nuclei located near the base of the cells?

Simple columnar epithelium

What is the function of goblet cells in the intestinal epithelium?

Secretion of mucus

Which component of the small intestine is most affected by gluten sensitivity (coeliac disease), resulting in flattened mucosal surface?

Villi

What is the main purpose of histological staining?

To deposit markers or characteristic colors on biological entities

What is the initial step required to prepare formalin-fixed paraffin-embedded (FFPE) sections for staining?

Removal of wax

What happens during the process of staining tissue sections with an aqueous staining solution?

Dyes and reagents enter tissues due to coulombic attractions

What is the final step in preparing stained tissue sections to be permanent?

Mounting with coverslip using media

What is the purpose of rehydrating formalin-fixed paraffin-embedded (FFPE) sections before staining?

To facilitate penetration of staining solutions into tissues

What is the main purpose of acidic stains in histology?

To owe their colour to the anion, with sodium usually being the cation

What is the main characteristic of basic stains in histology?

They owe their colour to the cation, with the anion commonly being a chloride

What distinguishes neutral stains from acidic and basic stains in histology?

They owe their colour to both acid and basic elements, staining 'neutral' elements

What is the main purpose of enzyme histochemical staining in histology?

To react with added substrate and a chromogen to produce a coloured insoluble end product

What is the main purpose of immunohistochemical staining in histology?

To bind selectively to antigens in cells and/or tissues

What is the main effect of neutral stains on tissue sections in histology?

To owe their colour to both acid and basic elements, staining 'neutral' elements

What is the purpose of using a mordant in conjunction with haematoxylin?

To create a 'dye lake' with a positive charge

Why are sections stained with routine basic dyes usually mounted in non-aqueous media?

To prevent dye extraction

What is the reason for stains not being taken up into every part of the tissue?

Rate of reagent uptake

How does fixation affect staining?

Different fixatives retain substances to different extents

What influences staining in specimen geometry?

All of the above

What is the primary factor affecting sensitivity in demonstration methods?

Retention of target in tissues

What are the main aims of the Haematoxylin & Eosin (H&E) stain?

Add contrast to sections and react with specific targets

Why do staining protocols vary between laboratories?

To account for differences in laboratory conditions and preferences

What does the acronym 'SOP' stand for in the context of staining protocols?

Standard Operational Procedure

How does specimen geometry influence staining equilibrium?

Complex geometries can arise when preparing smears from epithelia

What is an artifact related to poor section cutting that produces sections comprised of alternating thick and thin strips?

Chatter

What is the primary purpose of demonstration methods in histological staining?

To add contrast to sections

Study Notes

Histological Staining

  • Tissue sections need to be stained to visualize tissue elements and structures.
  • Special stains are used to selectively demonstrate specific tissue elements for research purposes.

Preparation of Tissue Sections

  • Without staining, tissue sections are difficult to interpret and may appear transparent.
  • Immunohistochemistry is used to visualize specific proteins or antigens in tissue sections.
  • The main component of cells is water, making up 80% of their composition.

Types of Epithelium

  • Simple columnar epithelium is characterized by a single layer of tall, narrow cells with their nuclei located near the base of the cells.
  • Goblet cells in the intestinal epithelium produce mucin, which helps to lubricate and protect the intestine.

Gluten Sensitivity

  • The component of the small intestine most affected by gluten sensitivity (coeliac disease) is the mucosal surface, resulting in a flattened appearance.

Histological Staining Purpose

  • The main purpose of histological staining is to enhance the visibility of tissue structures and components.

Preparing FFPE Sections

  • The initial step in preparing formalin-fixed paraffin-embedded (FFPE) sections for staining is to rehydrate them.
  • Rehydrating FFPE sections allows for the removal of paraffin and the restoration of the tissue's natural structure.

Staining Process

  • During staining, an aqueous staining solution penetrates the tissue section, and the dye binds to specific tissue components.
  • The final step in preparing stained tissue sections is to mount them in a medium, such as a solvent, to make them permanent.

Stain Characteristics

  • Acidic stains are used to stain basophilic structures, such as nuclei and cytoplasm.
  • Basic stains are used to stain acidophilic structures, such as collagen and cytoplasmic inclusions.
  • Neutral stains do not have a specific affinity for acidic or basic structures and are used to stain general tissue structures.

Enzyme and Immunohistochemical Staining

  • Enzyme histochemical staining is used to demonstrate the activity of enzymes in tissue sections.
  • Immunohistochemical staining is used to detect specific proteins or antigens in tissue sections.

Stain Effects

  • Neutral stains have a general staining effect on tissue sections.
  • Acidic stains are negatively charged and bind to positively charged tissue components.
  • Basic stains are positively charged and bind to negatively charged tissue components.

Mordant and Haematoxylin

  • A mordant is used in conjunction with haematoxylin to enhance the staining of basophilic structures.

Mounting Stained Sections

  • Sections stained with routine basic dyes are usually mounted in non-aqueous media to prevent the dye from being washed out.

Stain Uptake

  • Stains are not taken up into every part of the tissue due to variations in tissue structure and composition.

Fixation and Staining

  • Fixation affects staining by altering the tissue's structure and composition, which can affect the binding of dyes.

Specimen Geometry and Staining

  • Specimen geometry influences staining equilibrium, which can affect the uniformity of staining.

Sensitivity and Demonstration Methods

  • The primary factor affecting sensitivity in demonstration methods is the amount of antigen or protein present in the tissue section.
  • The primary purpose of demonstration methods is to visualize specific tissue components or structures.

Haematoxylin & Eosin (H&E) Stain

  • The main aims of the Haematoxylin & Eosin (H&E) stain are to provide a general overview of tissue structure and to identify specific tissue components.

Staining Protocols and SOP

  • Staining protocols vary between laboratories due to differences in equipment, reagents, and personnel.
  • SOP stands for Standard Operating Procedure, which outlines the step-by-step protocol for a specific staining technique.

Specimen Geometry and Staining Equilibrium

  • Specimen geometry influences staining equilibrium, which can affect the uniformity of staining.

Artifacts in Staining

  • A chunking artifact is related to poor section cutting and produces sections comprised of alternating thick and thin strips.

Test your knowledge on the principles and theory of histological staining with this quiz. Learn about the main types of staining actions and enhance your understanding of the techniques used in pathology.

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