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Periarterial macrophage sheaths (ellipsoids) in cat spleen--an electron microscope study
The American Journal of Anatomy
|June 1, 1981
Summary
Periarterial macrophage sheaths (PAMS) in cat spleens are key for clearing blood particles. These structures adapt to blood flow, with endothelial cells potentially regulating blood cell passage.
Area of Science:
- Spleen histology
- Immunology
- Vascular biology
Background:
- Periarterial macrophage sheaths (PAMS) are crucial for particle clearance in the spleen's red pulp.
- Previous terminology like "ellipsoids" did not fully capture PAMS structure and function.
Purpose of the Study:
- To investigate the ultrastructure of PAMS and their associated arterial capillaries in cat spleens.
- To understand how PAMS morphology changes with spleen congestion and contraction.
Main Methods:
- Transmission electron microscopy was used to examine PAMS and arterial capillaries.
- Thorotrast, a colloidal thorium dioxide suspension, was injected to label macrophages.
Main Results:
- PAMS form a meshwork of reticular cells and fibers surrounding arterial capillaries, housing macrophages.
- PAMS exhibit variable states of compression and relaxation, influenced by plasma infiltration.
- Macrophages contain phagocytized debris and Thorotrast, with extensive interdigitation.
- Endothelial cells of capillaries feature interdigitating processes and potential slits for blood cell passage, containing numerous intermediate filaments.
Conclusions:
- PAMS are dynamic structures involved in blood filtration and particle clearance.
- The spleen's vascular endothelium, rich in intermediate filaments, likely responds to hemodynamic changes, regulating blood flow and cell passage through interendothelial slits.