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Updated: Oct 12, 2025
Rigid Embedding of Fixed and Stained, Whole, Millimeter-Scale Specimens for Section-free 3D Histology by Micro-Computed Tomography
Published on: October 17, 2018
A Novel Technique for Preparation, Staining, and Visualization of Tissue with Metal Implants and Extraskeletal
R A Mukhamadiyarov1, L A Bogdanov2, S V Mishinov3
1Senior Researcher, Laboratory for Fundamental Aspects of Atherosclerosis, Department of Experimental and Clinical Cardiology; Research Institute for Complex Issues of Cardiovascular Diseases, 6 Sosnovy Blvd, Kemerovo, 650002, Russia.
Abstract:
The aim of the study was to evaluate the efficacy of a novel technique for preparation, staining, and visualization of tissues containing extra-skeletal mineralization areas, all-metal implants or their prototypes for their subsequent examination using scanning electron microscopy in the backscattered electron mode.
Materials And Methods:
After fixation in 10% formalin (24 h), the biomaterial (a titanium nickelide plate with the surrounding tissues after subcutaneous implantation, patented titanium alloy plates with the surrounding tissues after cranioplasty, primary and secondary calcified atherosclerotic plaques) were fixed with 1% osmium tetroxide (12 h) and then stained with 2% aqueous solution of osmium tetroxide (48 h). The samples were further stained with 2% alcoholic uranyl acetate (5 h), dehydrated with isopropanol (5 h) and acetone (1 h), impregnated with a mixture of acetone and epoxy resin Epon (1:1, 6 h) and then embedded into a fresh portion of epoxy resin (24 h), which was followed by polymerization at 60°C. After grinding and polishing, epoxy blocks were counterstained with lead citrate (7 min) and sputter-coated with carbon, then the samples were visualized by scanning electron microscopy in the backscattered electron mode. The elemental composition was studied using X-ray microanalysis.
Results:
The developed technique allows obtaining high-quality images at five thousand-fold magnifications, provides the possibility to identify the shape and structure of intact metal and mineral inclusions, and to type the surrounding cells, distinguishing mesenchymal and immunocompetent cells by shape and cytoplasmic content. Apart from connective tissue capsule thickness and leukocyte infiltration, this technique makes it possible to estimate the number and area of newly formed small-caliber vessels representing a surrogate marker of inflammation.
Conclusion:
The proposed technique provides the possibility to investigate adequately the structure of samples when their sectioning is impossible or significantly complicated, with image quality remarkably higher than that obtained by light microscopy.
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01:13Special Staining Techniques
01:03Fixation and Sectioning
The simplest type of preparation is the wet mount, in which the specimen is placed in a drop of liquid on the slide. A liquid specimen can be directly deposited on the slide using a dropper. Solid specimens, such as skin scraping, can be placed on the slide before adding a drop of liquid to prepare the wet mount. Sometimes the liquid is simply water, but stains are often added...
01:17Studying the Cytoskeleton
01:20Preparation of Samples for Electron Microscopy