What histologic feature marks the transition zone at the corneal periphery (limbus) with stem cell presence?

• A. Palisades of Vogt and the limbal stem cell niche
• B. Descement’s folds
• C. Keratocytes in stroma
• D. Bowman’s layer presence

Answer: (A)

The stem cell pool for renewing the corneal epithelium sits in the limbal region, where the transition from cornea to conjunctiva occurs. The histologic feature that marks this limbal transition and houses the stem cells is the Palisades of Vogt—the radial fibrovascular ridges and crypts in the limbal epithelium and nearby stroma. These structures create a niche that supports undifferentiated stem cells in the basal layer of the limbal epithelium, supplying new epithelial cells to the cornea as needed and maintaining the corneal surface.

Descemet’s folds are folds of Descemet’s membrane associated with endothelial changes and do not indicate a stem cell niche. Keratocytes in the stroma reside in the corneal stroma rather than at the epithelial-stromal boundary and do not define the limbal stem cell region. Bowman's layer is a separate acellular layer between the epithelium and stroma and does not mark the stem cell zone.