Introduction to Histology

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Questions and Answers

What does in situ hybridization primarily detect?

Specific proteins in tissues

Nucleic acids in tissues or cells (correct)

Intracellular organelles

Antibodies in blood samples

Which type of immunostaining utilizes a single-labeled antibody?

Fluorescence in situ hybridization

Indirect immunostaining

Immunogold microscopy

Direct immunostaining (correct)

What is the main purpose of using gold particles in immunogold microscopy?

To interact with protein antigens directly

To cause electron scatter for better imaging (correct)

To enhance the color of the samples

To stain the nucleus specifically

Which of the following describes the use of small molecule fluorophores?

Target intracellular organelles selectively Signup and view all the answers

In real-time interventional fluorescence imaging for cancer, what aspect is identified during surgery?

Tumor margins Signup and view all the answers

What is indicated by positive staining in transmission electron microscopy (TEM)?

Increased density of cell components Signup and view all the answers

What type of antibodies does indirect immunostaining use?

Both primary and secondary antibodies Signup and view all the answers

What type of hybridization uses fluorescently labeled nucleic acid probes?

Fluorescence in situ hybridization Signup and view all the answers

What is the main advantage of phase contrast microscopy over bright field microscopy?

Improved contrast Signup and view all the answers

What is the purpose of Masson's trichrome stain in histology?

To stain nuclei, cells, and collagen fibers Signup and view all the answers

What is the main application of confocal microscopy?

To increase the resolution of an imaged specimen Signup and view all the answers

What is the principle behind autoradiography?

Radioactive labeling of molecules to study their localization Signup and view all the answers

What is the main difference between bright field microscopy and differential interference contrast (DIC) microscopy?

DIC microscopy is better for imaging surface features Signup and view all the answers

What is the function of GFP in fluorescence microscopy?

To label proteins of interest Signup and view all the answers

What type of stain is Periodic Acid-Schiff (PAS)?

Special stain relying on a chemical reaction with tissues Signup and view all the answers

What is the purpose of Nissl stains in histology?

To visualize rough endoplasmic reticulum (rER) Signup and view all the answers

What is the main advantage of fluorescence microscopy over other types of microscopy?

Specific labeling of cellular components Signup and view all the answers

What is the purpose of enzyme histochemistry?

To identify enzyme location based on enzymatic activity Signup and view all the answers

Study Notes

Microscopy Techniques

Bright Field Microscopy: Visualizes live cells but has limitations in cellular detail due to similar optical densities among components.
Phase Contrast Microscopy: Enhances sample contrast; uses refractive properties to highlight dense regions (darker) and less dense regions (lighter).
Differential Interference Contrast (DIC) Microscopy: Modified phase contrast technique ideal for imaging surfaces; poor fixation or staining can lead to sample deterioration.

Staining Methods

Masson’s Trichrome Stain:
- Nuclei: black
- Muscle fibers: red/pink
- Collagen fibers and cartilage matrix: blue/green
Mallory Trichrome Stain:
- Nuclei: red
- Red blood cells and keratin: orange
- Collagen fibers, cartilage, and bone matrix: blue
Periodic Acid-Schiff (PAS): Stains polysaccharides (glycogen) and glycoproteins (mucins), making them bright pink, and highlights basement membranes.
Nissl Staining: Commonly uses Cresyl violet to visualize nuclei, nucleoli, and ribosomes, particularly in nervous tissues.

Fluorescence Techniques

Fluorescent Stains: Commonly used stains like DAPI and Hoechst specifically target DNA.
Fluorophores: Antibodies conjugated with fluorophores provide visualization of proteins in tissues, while fluorescent proteins like GFP label proteins of interest.
Confocal Microscopy: Enhances image resolution using lasers and pinholes to exclude out-of-focus light, resulting in sharper images.

Autoradiography

Utilizes radioactivity (e.g., Tritium 3H or Carbon 13) to study molecular interactions in living systems and characterize DNA synthesis.

Immunostaining Techniques

Direct Immunostaining: Involves a single labeled antibody that detects an antigen directly.
Indirect Immunostaining: Utilizes two antibodies—primary to detect the target antigen and secondary to amplify the signal.

Enzyme Histochemistry

Detects enzyme locations based on enzymatic activity for types like phosphatases and peroxidases through reaction products.

Hybridization Techniques

In Situ Hybridization: Detects specific sequences of DNA or RNA in tissues/cells using radioactive isotopes.
Fluorescence In Situ Hybridization: Uses fluorescently labeled probes for gene or mRNA detection in cells.

Gold Microscopy

Immunogold Microscopy: Uses electron-dense gold particles for visualization in Transmission Electron Microscopy (TEM), allowing for specific protein detection.

Staining Artifacts

Awareness of common artifacts in histological preparations is crucial for accurate interpretation of stains and tissue images.

Small Molecule Fluorophores

Target and label intracellular organelles like mitochondria and Golgi structures; applicable for tumor imaging and real-time surgical interventions.

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Description

Understanding and interpreting images obtained through different types of microscopy techniques, including bright field, phase contrast, and differential interference contrast microscopy. Learn about the advantages and limitations of each technique in visualizing cellular details.