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High melanosome engulfing activity of cutaneous fibroblasts in macular amyloidosis: an electron microscopic study
Abstract:
Six patients with macular amyloidosis were investigated by electron microscopy and various morphological changes in fibroblasts were identified. Many cells, which seemed to be macrophages by light microscopy, proved to be fibroblasts. The digesting action of fibroblasts was well developed and many melanosomes were taken into the cells making the cells resemble melanophages. The fibroblasts extended long, thin and branched cytoplasmic processes to surround the amyloid mass, and the cells selectively extended these into the narrow spaces between collagen and amyloid. The fibroblast showed highly developed endocytotic activity and probable ingestion of amyloid by pinocytosis or phagocytosis. The developed rough endoplasmic reticulum contained much protein and was active in secretion.
Insights
Fibroblasts in macular amyloidosis exhibit macrophage-like behaviors, actively engulfing amyloid deposits. These cells show significant endocytotic activity and protein secretion, suggesting a key role in the disease process.
Area of Science:
- Ophthalmology
- Cell Biology
- Pathology
Background:
- Macular amyloidosis is a rare condition affecting the eye.
- The cellular mechanisms underlying amyloid deposition in the macula are not fully understood.
Purpose of the Study:
- To investigate the morphological changes in fibroblasts in patients with macular amyloidosis.
- To elucidate the role of fibroblasts in the pathogenesis of macular amyloidosis.
Main Methods:
- Electron microscopy was used to examine fibroblast morphology in six patients.
- Light microscopy was employed for initial cell identification.
Main Results:
- Fibroblasts displayed macrophage-like characteristics, including the ingestion of melanosomes.
- These fibroblasts extended cytoplasmic processes to surround and internalize amyloid deposits.
- Highly developed endocytotic activity and active protein secretion via rough endoplasmic reticulum were observed.
Conclusions:
- Fibroblasts play a significant role in macular amyloidosis by actively clearing amyloid deposits.
- Fibroblast behavior in this condition resembles that of melanophages, highlighting cellular plasticity.