Staining plastic sections: a review of problems, explanations and possible solutions

Area of Science:

• Microscopy
• Materials Science
• Histology

Background:

• Staining difficulties in light and electron microscopy arise from hydrophobic embedding media physically excluding hydrophilic reagents.
• Incomplete infiltration of embedding media into tissues leads to poor staining.
• Tissue elements' density and hydration influence monomer exclusion.

Purpose of the Study:

• To explain the challenges in staining plastic-embedded tissues.
• To investigate the role of embedding media properties and reagent hydrophobicity in staining.
• To explore factors influencing monomer infiltration and tissue staining.

Main Methods:

• Analysis of physical exclusion principles in tissue embedding.
• Comparison of hydrophilic and hydrophobic staining reagent interactions with embedding media.
• Exploration of monomer-tissue interactions and fixative effects.

Main Results:

• Hydrophobic embedding media physically exclude hydrophilic staining reagents.
• Hydrophobic reagents can achieve generalized staining in hydrophobic media.
• Staining of plastic-free structures with hydrophilic reagents is rate-controlled.
• Similarities between hydrophilic and hydrophobic embedding media were observed.

Conclusions:

• The hydrophobicity of embedding media is a primary barrier to hydrophilic stain infiltration.
• Optimizing staining requires matching reagent properties to embedding media or considering alternative approaches.
• Further research into fixative and monomer-tissue reactions is needed to fully understand staining limitations.