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Light microscopic morphometric analysis of peroxisomes by automatic image analysis: advantages of immunostaining over
1Institut für Anatomie und Zellbiologie II, Universität Heidelberg, Federal Republic of Germany.
Insights
Post-embedding immunocytochemistry enables accurate light microscopic morphometry of peroxisomes, independent of section thickness. This method provides reliable results comparable to electron microscopy for studying peroxisome proliferation.
Area of Science:
- Cell Biology
- Microscopy Techniques
- Biochemistry
Background:
- Peroxisome morphometry is crucial for understanding cellular functions.
- Traditional methods like alkaline diaminobenzidine (DAB) staining have limitations in accuracy.
- Light microscopy offers advantages in speed and accessibility over electron microscopy.
Purpose of the Study:
- To evaluate the feasibility of light microscopic post-embedding immunocytochemistry for peroxisome morphometry.
- To compare this method with the classical alkaline DAB staining technique.
- To assess its accuracy and reliability for quantifying peroxisome proliferation.
Main Methods:
- Perfusion-fixed rat liver tissue was processed using LR White embedding or alkaline DAB staining.
- Immunostaining involved a monospecific antibody against catalase, followed by protein A-gold and silver intensification.
- Automatic image analysis was employed for morphometric determination of peroxisomal volume density.
Main Results:
- Immunostained sections showed peroxisomal volume density independent of section thickness.
- DAB-stained sections exhibited increased values with greater section thickness.
- Light microscopic morphometry using immunostaining yielded results comparable to electron microscopy for both volume density and proliferation.
Conclusions:
- Post-embedding immunocytochemistry is a reliable method for light microscopic morphometry of peroxisomes.
- This technique overcomes the section thickness dependency of DAB staining.
- It offers a valuable, accurate alternative to electron microscopy for studying peroxisome proliferation.
Abstract:
The feasibility of light microscopic post-embedding immunocytochemistry for morphometry of peroxisomes using automatic image analysis was investigated and compared with the classical alkaline DAB method. Perfusion-fixed rat liver tissue was either embedded in LR White or incubated in the alkaline diaminobenzidine (DAB) medium for cytochemical visualization of catalase. Sections from the LR White-embedded material were incubated with a monospecific antibody against catalase, followed by protein A-gold and silver intensification. Determination of peroxisomal volume density in sections of different thickness revealed that the values increased with section thickness in DAB-stained sections but were unaffected in immunostained preparations. Moreover, the absolute value for volume density of peroxisomes, as determined by light microscopy in immunostained sections, was quite close to the value obtained by analysis of electron microscopic preparations. Finally, morphometric analysis of bezafibrate-induced peroxisome proliferation revealed that the ratio of proliferation obtained by light microscopy in immunostained sections was very close to the results obtained by electron microscopic morphometry. The main advantage of post-embedding immunostaining for light microscopic morphometry is that it restricts the immunocytochemical reaction product to the surface of the section, thus making it independent of section thickness.