Interspecies comparative morphological evaluation of the corneal epithelial stem cell niche: a pilot observational...

Area of Science:

• Comparative ophthalmology
• Histology
• Animal models

Background:

• Corneal and limbal morphology are crucial for corneal epithelial maintenance.
• Histological examination of ten species was performed to understand these structures.

Purpose of the Study:

• To evaluate differences in corneal thickness and epithelium across species.
• To examine Bowman's layer, limbal epithelial cells, and stromal morphology.

Main Methods:

• Histological analysis of corneal sections from Aves, Amphibia, and Mammalia.
• Staining with hematoxylin and eosin and periodic acid-Schiff reaction.
• Microscopic photography and analysis of stained slides.

Main Results:

• Significant species-specific differences observed in corneal and limbal epithelia and stroma.
• Corneal epithelial thickness and cell layer count varied significantly.
• Bowman's layer was exclusively found in primates (orangutans, humans).
• Supranuclear melanin caps were noted in the limbal basal epithelium of orangutans, macaws, red pandas, and horses.

Conclusions:

• Supranuclear melanin capping may protect against ultraviolet radiation, similar to its role in epidermis.
• A potential relationship exists between limbal stem cell melanin capping and UV protection.