Practical considerations for birefringence microscopy of myelin structure: Microscope design and tissue processing...

Area of Science:

• Neuroscience
• Biophysics
• Microscopy

Background:

• Current optical microscopy methods are insufficient for high-resolution myelin imaging in postmortem brain tissue.
• Detecting microstructural myelin alterations in aging and neurodegenerative diseases requires sensitive imaging techniques.
• Minimizing myelin damage during tissue processing is critical for accurate structural analysis.

Purpose of the Study:

• To develop and validate an improved birefringence microscopy (BRM) system and image processing pipeline for efficient, high-throughput myelin imaging.
• To systematically assess the impact of common tissue processing steps on myelin structural integrity in rhesus monkey brain sections.
• To establish optimal sample preparation protocols for high-resolution myelin imaging using BRM.

Main Methods:

• Development of an advanced BRM system with fast piezoelectric rotational stages.
• Implementation of an image processing pipeline requiring only three images for birefringence parameter map determination.
• Systematic evaluation of tissue processing steps, including dehydration, mounting media, detergent permeabilization, and section thickness, on myelin structure.

Main Results:

• The enhanced BRM system significantly increases imaging speed and efficiency.
• Direct evidence shows that tissue mishandling during preparation causes significant myelin structural alterations.
• Optimal myelin imaging requires avoiding prolonged dehydration, using 85% glycerol as a mounting medium, omitting detergents, and selecting appropriate section thickness.

Conclusions:

• BRM is a sensitive, label-free technique for detailed myelin imaging and characterization.
• Optimized sample preparation is essential to preserve myelin structure and avoid artifacts.
• BRM, with proper tissue preservation, enables advanced studies of myelin pathology in disease.