Freeze-dried, plastic-embedded tissue preparation: a review

Area of Science:

• Biological Sciences
• Analytical Chemistry
• Microscopy

Background:

• Animal soft tissue preparation is crucial for morphological and analytical studies.
• Traditional methods may not adequately preserve water-soluble constituents.
• Novel preparation techniques are needed to enhance analytical capabilities.

Purpose of the Study:

• To evaluate the utility of freeze-dried, plastic-embedded specimens for animal soft tissue analysis.
• To assess the method's effectiveness in preserving intracellular water-soluble constituents.
• To identify advantages and limitations for various analytical techniques.

Main Methods:

• Specimen preparation involved rapid freezing, freeze-drying, osmic acid vapor fixation, and epoxy resin embedding.
• Analysis included light and electron microscopy, histochemical procedures, and electron probe microanalysis.
• Considerations for energy dispersive X-ray spectroscopy (Si(Li) detectors) and wavelength spectrometers were addressed.

Main Results:

• The method effectively preserves intracellular water-soluble constituents and electrolytes present at cryofixation.
• Embedded samples are stable for long-term storage and compatible with various staining and analytical techniques.
• A significant limitation is the poor preservation of extracellular solute distribution.

Conclusions:

• Freeze-dried, plastic-embedded tissue is a valuable preparation for quantitative intracellular analysis, particularly for electrolytes.
• The technique offers advantages for electron probe microanalysis and microscopy but requires careful consideration of embedding material effects.
• Further optimization may be needed to improve extracellular space preservation.