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Swelling of mitochondria in immersion-fixed liver tissue. Effect of various fixatives and of delayed fixation
Abstract:
In order to study the occurrence of swollen and disrupted mitochondria in tissue preserved for electron microscopy by ordinary fixation methods, liver tissue from miniature pig fetuses was immersion-fixed in fixatives with various types and concentrations of fixing agents and vehicles. Also commercial and purified products have been tested, different fixation times and temperatures as well as the consequences of a short rinsing in buffer solutions prior to fixation. Furthermore, the significance of delayed fixation (autolysis) was studied. It was found that swollen and disrupted mitochondria occur predominantly in liver cells exposed to low concentrations of glutaraldehyde. It is shown that this phenomenon is a result of a specific effect of glutaraldehyde on the mitochondrial membranes. It is not accompanied by parallel changes of other organelles or nuclei, and it not provoked by other fixing agents, vehicles or by delayed fixation (autolysis).
Insights
Low glutaraldehyde concentrations cause mitochondrial swelling and disruption in electron microscopy. This specific effect on mitochondrial membranes is not seen with other fixatives or delayed fixation.
Area of Science:
- Cell Biology
- Microscopy Techniques
- Histology
Background:
- Standard fixation methods for electron microscopy can alter cellular structures.
- Mitochondria are particularly sensitive to fixation artifacts, impacting ultrastructural studies.
Purpose of the Study:
- To investigate the causes of swollen and disrupted mitochondria in preserved liver tissue.
- To determine the specific role of glutaraldehyde concentration in mitochondrial artifact formation.
Main Methods:
- Immersion fixation of miniature pig fetal liver tissue using varied fixatives, concentrations, and vehicles.
- Testing different fixation times, temperatures, buffer pre-rinsing, and delayed fixation (autolysis).
- Evaluating the impact of commercial vs. purified glutaraldehyde products.
Main Results:
- Swollen and disrupted mitochondria predominantly observed in liver cells exposed to low glutaraldehyde concentrations.
- This mitochondrial artifact is attributed to a specific effect of glutaraldehyde on mitochondrial membranes.
- No parallel changes were noted in other organelles or nuclei, and the effect was not induced by other fixatives or autolysis.
Conclusions:
- Low glutaraldehyde concentrations are a primary cause of mitochondrial artifacts in electron microscopy.
- Understanding glutaraldehyde's specific membrane effects is crucial for accurate ultrastructural interpretation.
- Optimized fixation protocols are essential to avoid mitochondrial artifacts in histological samples.