Bicomponent keratohyalin in normal human ridged skin.

Area of Science:

• Dermatology
• Cell Biology
• Histology

Background:

• Bicomponent keratohyalin was previously identified only in rat epidermis, human sweat ducts, and fetal nail organs.
• In normal human epidermis, keratohyalin typically appears homogeneous and stellate.
• Pathological conditions, such as palmoplantar keratoses, have shown bicomponent keratohyalin, suggesting a link to abnormal keratinization.

Purpose of the Study:

• To investigate the morphological characteristics of keratohyalin in normal human plantar epidermis.
• To compare keratohyalin in ridged skin with that of non-ridged skin and other known bicomponent keratohyalin structures.

Main Methods:

• Electron microscopy was used to examine the ultrastructure of keratohyalin granules in normal human plantar epidermis.
• Morphological and electron density differences were analyzed and compared between different skin types and cell locations.

Main Results:

• Normal human ridged skin displayed distinct morphological differences in keratohyalin compared to non-ridged skin.
• A striking feature was the presence of two components with differing electron densities within keratohyalin granules in upper granular cells of ridged skin.
• The electron-dense component formed the main granule, while a less-dense component attached to it. These differed from bicomponent keratohyalin in sweat ducts and rat epidermis.

Conclusions:

• Normal human ridged skin possesses at least two distinct types of keratohyalin proteins.
• These keratohyalin types can be differentiated using electron microscopy.
• The identified keratohyalin structures in ridged skin are unique and distinct from those in human non-ridged skin and previously described bicomponent keratohyalin.