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Ultrahistochemical studies on the moderately electron dense bodies in teleostean endocardial cells
Abstract:
The staining properties of phosphotungstic acid (PTA) on moderately electron dense bodies (MDB), are studied in the endocardium of Gadus morrhua. In MDB fixed in aldehydes only, and stained with PTA at a low pH (0-1), Intensly electron dense material occurs on and beneath the limiting membrane. This latter area displays a declining electron density when stained with PTA solutions in which the pH is raised from 1 to 4. At pH greater than 5 the peripheral matrix appears nearly unstained. Collagen fibres fixed as above, and then stained with PTA at a low pH, appear electron dense. These results suggest that the peripheral matrix of the MDB consists mainly of basic proteins.
Insights
Phosphotungstic acid (PTA) staining reveals that moderately electron dense bodies (MDB) in fish endocardium contain basic proteins. This finding is based on how MDB and collagen fibers react to PTA at different pH levels.
Area of Science:
- Electron microscopy
- Biochemistry
- Cell biology
Background:
- Moderately electron dense bodies (MDB) are cellular structures found in the endocardium of fish.
- The composition of MDB and their interaction with staining agents requires further elucidation.
Purpose of the Study:
- To investigate the staining properties of phosphotungstic acid (PTA) on MDB in the endocardium of Gadus morrhua.
- To determine the protein composition of MDB based on their reaction to PTA at varying pH levels.
Main Methods:
- Fixation of Gadus morrhua endocardium in aldehydes.
- Staining with phosphotungstic acid (PTA) at controlled pH levels (0-5).
- Electron microscopy to observe MDB and collagen fiber staining patterns.
Main Results:
- At low pH (0-1), PTA intensely stained MDB on and beneath the limiting membrane.
- Increasing PTA pH from 1 to 4 caused declining electron density in the MDB's peripheral matrix.
- At pH > 5, the MDB peripheral matrix was unstained, while collagen fibers remained electron dense at low pH.
Conclusions:
- The peripheral matrix of MDB in Gadus morrhua endocardium is primarily composed of basic proteins.
- PTA staining at different pH levels is a reliable method for identifying basic proteins in MDB.