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Meesmann's corneal dystrophy: ultrastructural features
Abstract:
Ultrastructural studies were done on a cornea obtained at the time of lamellar keratoplasty from a patient with the clinical diagnosis of Meesmann's corneal dystrophy. Light microscopy showed in the corneal epithelium the typical tiny cysts containing cellular debris and a homogeneous substance that reacted with periodic acid and Schiff's reagent and stained with Hale's colloidal iron; as well, the basement membrane was markedly thickened. Electron microscopy revealed that the cysts had a corrugated or microvillous wall, consistent with acantholysis. The epithelial cells were rich in glycogen, and many contained the peculiar substance described by others in Meesmann's corneal dystrophy. This substance appeared to be derived from the tonofilaments and was in close relation to the desmosomes. The thick basement membrane showed secondary changes, with one thick zone that was rich in collagen fibrils mimicking abnormal anchoring fibrils and one thin zone that was poor in fibrils but had frequent intercalated fibroblasts and probably represented a repair phenomenon. There was no apparent modification of Bowman's layer or the superficial stroma.
Insights
Meesmann
Area of Science:
- Ophthalmology
- Cell Biology
- Histology
Background:
- Meesmann's corneal dystrophy is a rare genetic eye disorder.
- Characterized by epithelial cysts and basement membrane thickening.
- Ultrastructural analysis is crucial for understanding disease mechanisms.
Purpose of the Study:
- To investigate the ultrastructural features of Meesmann's corneal dystrophy.
- To elucidate the cellular basis of cyst formation and basement membrane changes.
Main Methods:
- Lamellar keratoplasty tissue analysis.
- Light microscopy and electron microscopy.
- Histochemical staining (PAS, Hale's colloidal iron).
Main Results:
- Epithelial cysts with corrugated walls (acantholysis) observed.
- Epithelial cells rich in glycogen and containing a unique substance linked to tonofilaments and desmosomes.
- Markedly thickened basement membrane with collagen fibrils and fibroblasts, suggesting repair.
Conclusions:
- Ultrastructural findings confirm acantholysis and glycogen accumulation in Meesmann's corneal dystrophy.
- Basement membrane thickening involves collagen deposition and fibroblast activity, possibly a reparative response.
- Provides detailed insights into the pathogenesis of this corneal dystrophy.