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James Kenneth Kubilus, Carolina Zapater i Morales, Thomas Linsenmayer; Analysis of the corneal-scleral junction in the embryonic chicken. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5828.
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© ARVO (1962-2015); The Authors (2016-present)
In the healthy adult cornea, mature epithelial cells at the apical surface undergo desquamation and are replaced by new cells. These new epithelial cells are derived from the limbal stem cell niche, thought to reside in the palisades of Vogt. While much research has sought to characterize and describe these corneal epithelial stem cells, little is known about how these cells and their niche are formed during embryonic development. The studies presented here investigated the early embryonic development of the corneal limbal junction.
Embryonic chicken corneas from embryonic day 5 (E5) through E14 were labeled with the lipophilic dye (DiI). This time-course of DiI labeled corneas was sectioned and labeled using immunohistochemistry (IHC) for epithelial and limbal markers, including keratin 12, e-cadherin, n-cadherin, p63 and ZO-1. Embryonic corneas were imaged by scanning electron microscopy (SEM).
DiI applied to the corneal surface between the ages of E5 through E7.5 spread throughout the corneal epithelium and into the sclera. At E8 DiI diffusion was limited to within the corneal epithelium and did not spread past the corneal-scleral junction. Similarly, after E8 DiI placed in the sclera did not diffuse through the junction into the cornea. SEM of corneas at E8 showed increased intracellular space suggestive of changes in cell junction proteins that correlated with IHC.
Changes in the cell junctions at the corneal-scleral limbus correlate with the development of a diffusion barrier between the cornea and sclera. This barrier may have a functional role in establishing the corneal stem cell niche.
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