Histological Staining Principles Lecture 4 Quiz

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.