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A method for processing fluorescent labelled tissue into methacrylate: a qualitative comparison of four tracers
C L Sangster1, M P Galea, R Fan
1School of Physiotherapy, University of Melbourne, Parkville, Victoria, Australia.
Journal of Neuroscience Methods
|September 24, 1999
Summary
This study developed a method to preserve fluorescent tracers in embedded neural tissue. Fast Blue and Diamidino Yellow tracers require inert dehydration for optimal retention in methacrylate-embedded neurons.
Area of Science:
- Neuroscience
- Histology
Background:
- Retrograde tracing is crucial for mapping neural circuits.
- Preserving fluorescence in embedded tissue is challenging for quantitative stereology.
Purpose of the Study:
- To develop and evaluate a technique for preserving fluorescence in retrogradely labeled neurons embedded in methacrylate resin.
- To compare the efficacy of different retrograde tracers and dehydration methods.
Main Methods:
- Four retrograde tracers (Fast Blue, Diamidino Yellow, tetramethylrhodamine dextran, fluorescein dextran) were applied to rat sciatic nerves.
- Tracer application methods included direct crystal application and nerve dipping.
- Two dehydration methods were compared: conventional alcohol and inert methacrylate infiltration.
- Labeled motoneurons in lumbar spinal cord sections were mapped using fluorescence microscopy.
Main Results:
- Direct tracer crystal application labeled more motoneurons than dipping.
- Fast Blue resulted in significantly more labeled motoneurons compared to tetramethylrhodamine dextran.
- All tested tracers maintained fluorescence after methacrylate embedding.
- Fast Blue and Diamidino Yellow required inert dehydration, while tetramethylrhodamine dextran and fluorescein dextran were compatible with conventional dehydration.
Conclusions:
- Fluorescent tracers can be successfully retained in methacrylate-embedded tissue for quantitative stereological analysis.
- The choice of dehydration method is critical and depends on the specific fluorescent tracer used.
- This technique enhances the potential for detailed quantitative studies of neural connectivity.