Histological Tissue Preparation Quiz

Histological Tissue Preparation

• Tissue Fixation: Crucial for stabilizing tissue structure, preventing decay, and preserving its integrity. Formaldehyde is a common fixative.

• Fixative Examples: Formaldehyde is a common tissue fixative.

• Ethyl Alcohol's Role: Removes water from the tissue, a critical step leading to a more solid tissue.

• Clearing Role: Replaces alcohol with a clearing agent (e.g., xylene), allowing the paraffin to permeate the tissue. Xylene is frequently used for this purpose

• Tissue Preparation Steps: Fixation is the first step in tissue preparation.

• Clearing Agents: Xylene is a common clearing agent.

• Tissue Sectioning: Thin sections enable light penetration during microscopy. This is essential for viewing the prepared tissue.

• Types of Microtomes: Cryostat microtomes are for frozen tissues, while rotary microtomes are used for paraffin-embedded tissues.

• H&E Staining: Hematoxylin stains the nucleus (typically dark blue/purple) and eosin stains the cytoplasm (typically pink/red).

• Hematoxylin Binding: Hematoxylin is a basic dye, binding to acidic components like DNA and RNA.

• Eosin Staining: Eosin is an acidic dye, staining basic cellular components like proteins that are located in the cytoplasm.

• Embedding Importance: Embedding ensures that the tissue is ready for sectioning and preserves its shape throughout the staining and mounting process.

• Staining After Embedding: Staining is typically done after embedding to facilitate visualizing and identifying cell components.

• PAS Staining: This stain is used to highlight carbohydrates in tissues.

• Order of Steps: The steps typically proceed as follows: Fixation, Dehydration, Clearing, Embedding, Sectioning, Staining. Embedding happens after clearing, and staining happens after sectioning.