Evaluation of a preparative method for x-ray microanalysis of soft tissues

Area of Science:

• Electron microscopy and microanalysis
• Cell biology and histology
• Biophysics and biochemistry

Background:

• Accurate elemental analysis in biological tissues requires preserving both cellular morphology and natural elemental distributions.
• Cryopreparative techniques are crucial for minimizing artifacts introduced during sample preparation for microanalysis.

Purpose of the Study:

• To evaluate cryopreparative methods for producing freeze-dried tissue sections suitable for electron probe microanalysis.
• To assess the preservation of cellular structure and elemental distributions under various experimental conditions.

Main Methods:

• Adapted cryopreparative methods for radioautography to create freeze-dried sections of soft tissues.
• Analyzed mouse pancreas and model solutions (BSA, gelatin with salts) using scanning electron microscopy with energy-dispersive X-ray detection.
• Evaluated cellular morphology, ice crystal formation, elemental distribution, section thickness, and tissue excision effects.

Main Results:

• Cellular morphology of pancreatic acinar cells was well preserved, with distinct cellular and subcellular structures visible.
• Ice crystal formation in bovine serum albumin sections had minimal impact on elemental analysis at standard magnifications.
• No significant elemental redistribution or translocation was observed due to tissue excision or section thickness variations (2-4 µm).

Conclusions:

• The adapted cryopreparative method is valid for preparing soft tissues for electron probe microanalysis of nuclear, cytoplasmic, and secretory compartments.
• The method's limitations arise only when analyses are performed at extremely high magnifications, potentially within single ice crystals.