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Pathogenesis of monilethrix: computer stereography and electron microscopy.
M Ito1, K Hashimoto, K Katsuumi
1Department of Dermatology, Niigata University School of Medicine, Japan.
The Journal of Investigative Dermatology
|August 1, 1990
Summary
Monilethrix, a hair shaft defect, involves alternating nodes and internodes. This study reveals cell abnormalities in the hair matrix, particularly affecting cortical cells, leading to hair thinning.
Area of Science:
- Dermatology
- Genetics
- Cell Biology
Background:
- Monilethrix is a rare hereditary hair disorder characterized by fragile, beaded hair.
- The precise cellular mechanisms underlying hair shaft abnormalities in monilethrix remain incompletely understood.
Observation:
- Scanning electron microscopy revealed the characteristic beaded appearance of monilethrix hairs.
- Three-dimensional reconstructions demonstrated reduced hair shaft diameter, primarily in the keratogenous zone, cortex, and cuticle.
- Transmission electron microscopy identified significant hair matrix cell degeneration and disarray of cortical tonofibrils.
Findings:
- Degeneration of hair matrix cells and cortical cells was observed, with invaginations of cuticle into the cortex.
- Cytoplasmic vacuolations and abnormal tonofibril formation were consistently present in affected hair and follicles.
- Hair matrix damage appears to occur independently in individual hairs, not in a synchronized manner.
Implications:
- The findings suggest an inherent cellular abnormality within the hair tissue in monilethrix.
- Severe abnormalities particularly impact cortical cells, leading to reduced cell numbers and hair shaft thinning.
- Understanding these cellular defects could inform future therapeutic strategies for monilethrix.