Stem Sectioning and Staining Techniques

Study Notes

Stem Sectioning and Staining

Sectioning Techniques:

Hand Sectioning: Cutting stem sections using a razor blade or sharp knife, typically used for thick stems or when a microtome is not available.
Microtome Sectioning: Using a microtome to cut thin sections (5-20 μm) of stem tissue, providing higher resolution and more precise control.
Cryosectioning: Freezing stem tissue and cutting sections using a cryostat, often used for soft or delicate tissues.

Staining Techniques:

Temporary Stains: Used for quick observation, such as toluidine blue or methylene blue, which can be easily removed.
Permanent Stains: Used for long-term preservation and observation, such as safranin and fast green, which are more resistant to fading.

Common Stains for Stem Sectioning:

Safranin and Fast Green: A combination stain for general histology, differentiating between lignified and non-lignified tissues.
Toluidine Blue: A metachromatic stain for revealing cellulose, pectin, and lignin in plant cell walls.
Methylene Blue: A basic dye for staining plant cell walls and nucleic acids.

Preparation and Fixation:

Fixation: Using chemicals like formaldehyde, ethanol, or acetic acid to preserve stem tissue and prevent degradation.
Dehydration: Gradually replacing water in the tissue with solvents like ethanol or acetone to prepare for embedding.
Embedding: Infiltrating the tissue with a resin or wax to provide support and stability for sectioning.

Mounting and Observation:

Mounting Media: Using a medium like Canada balsam or Permount to attach the section to a microscope slide.
Microscopy: Observing the stained sections using a light microscope to examine stem tissue structure and organization.

Stem Sectioning and Staining

Sectioning Techniques

Hand sectioning uses a razor blade or sharp knife to cut stem sections, ideal for thick stems or when a microtome is unavailable.
Microtome sectioning cuts thin sections (5-20 μm) of stem tissue, providing higher resolution and precise control.
Cryosectioning freezes stem tissue and cuts sections using a cryostat, suitable for soft or delicate tissues.

Staining Techniques

Temporary stains like toluidine blue or methylene blue are used for quick observation and can be easily removed.
Permanent stains like safranin and fast green are used for long-term preservation and observation, resisting fading.

Common Stains for Stem Sectioning

Safranin and fast green combination stain differentiates between lignified and non-lignified tissues in general histology.
Toluidine blue is a metachromatic stain revealing cellulose, pectin, and lignin in plant cell walls.
Methylene blue is a basic dye for staining plant cell walls and nucleic acids.

Preparation and Fixation

Fixation uses chemicals like formaldehyde, ethanol, or acetic acid to preserve stem tissue and prevent degradation.
Dehydration gradually replaces water in the tissue with solvents like ethanol or acetone to prepare for embedding.
Embedding infiltrates the tissue with a resin or wax to provide support and stability for sectioning.

Mounting and Observation

Mounting media like Canada balsam or Permount attach the section to a microscope slide.
Microscopy uses a light microscope to examine stained sections and observe stem tissue structure and organization.

Description

This quiz covers different methods of sectioning and staining stem tissue, including hand sectioning, microtome sectioning, and cryosectioning. It's essential for understanding plant anatomy and biology.