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Diluted and undiluted Mercox severely destroy unfixed endothelial cells. A light and electron microscopic study using
J Gassner1, A Lametschwandtner, T Weiger
1Department of Experimental Zoology, University of Salzburg, Austria.
Abstract:
Mercox is a methylmethacrylate-based resin which is widely used for vascular corrosion casting with subsequent scanning electron microscopic analysis. In the present study the effect of undiluted and diluted Mercox (4 + 1; volume + volume; Mercox: monomeric methyl-methacrylate (MMA); 0.02 g catalyst MA/ml Mercox) and methyl-methacrylate with and without catalyst MA (0.625 g/10 ml MMA) on fixed and unfixed endothelial cells was studied. Light microscopy (LM) of cultured capillary endothelial cells (ECs), which were replicated with diluted or undiluted Mercox shows degranulation and membrane perturbation of ECs, while no morphological changes occur in glutaraldehyde-prefixed ECs. Scanning electron microscopy (SEM) of replicas (= resin blocks) polymerized on prefixed ECs reveals unchanged ECs and replicas show many details. Unfixed ECs are destroyed and replicas reveal aberrant features. Transmission electron microscopy (TEM) of prefixed and unfixed ECs (cultured endothelial cells, endothelial cells of perfusion prefixed and of unfixed tadpole tail fin vessels) substantiates LM and SEM findings. Prefixed ECs resist Mercox without fine structural changes, while unfixed cells undergo destruction. It is recommended to fix vessels prior to casting. Extravasations in micro-vessels are considered to be caused by focal chemical destruction of endothelial cells.
Insights
Fixing endothelial cells before vascular corrosion casting with Mercox resin prevents cell destruction. Unfixed cells are damaged by the resin, impacting scanning electron microscopy analysis.
Area of Science:
- Biomaterials Science
- Cell Biology
- Microscopy Techniques
Background:
- Mercox resin is commonly used for vascular corrosion casting and scanning electron microscopy (SEM).
- The effects of Mercox and its components on endothelial cells (ECs) require detailed investigation.
- Understanding cellular responses to casting resins is crucial for accurate microvascular analysis.
Purpose of the Study:
- To evaluate the impact of Mercox resin and methyl methacrylate (MMA) on fixed and unfixed endothelial cells.
- To compare the morphological integrity of ECs and the quality of SEM replicas under different casting conditions.
- To determine the optimal preparation method for ECs in vascular corrosion casting.
Main Methods:
- Cultured capillary ECs and ECs from tadpole tail fin vessels were used.
- Cells were either prefixed with glutaraldehyde or left unfixed.
- Casting was performed using undiluted/diluted Mercox or MMA with/without catalyst, followed by LM, SEM, and TEM analysis.
Main Results:
- Mercox caused degranulation and membrane changes in unfixed ECs, while prefixed ECs remained morphologically intact.
- SEM of replicas from prefixed ECs showed detailed, unchanged ECs.
- SEM of replicas from unfixed ECs revealed destroyed cells and aberrant features.
- TEM confirmed that prefixed ECs resisted Mercox, while unfixed cells were destroyed.
Conclusions:
- Glutaraldehyde fixation is essential to preserve endothelial cell structure during Mercox vascular corrosion casting.
- Unfixed cells are chemically destroyed by Mercox, leading to artifacts in SEM analysis.
- Fixation prior to casting is recommended for accurate microvascular morphology and detailed SEM imaging.