Purpose:
To follow the histological events on the rabbit eye surface after total debridement of the corneal epithelium plus surgical excision of the limbus.
Methods:
The corneal epithelium of the right eyes of 12 male albino rabbits (Oryctolagus cuniculus) was totally scraped followed by surgical excision of the limbus plus 1.5mm of the adjacent conjunctiva. At 2 weeks, 1, 3 and 6 months after surgery the corneas of 3 rabbits per interval were processed for histology (PAS-hematoxylin) as well as for immunohistochemistry using AE5 as the primary antibody and goat anti-mouse IgG labeled with horseradish peroxidase as the secondary antibody.
Results:
At 2 weeks after surgery the corneal surface was covered by a loosely attached epithelium, negative for AE5, with few goblet cells. The anterior third of the stroma was fully vascularized on the periphery. These features remained unchanged on the corneal periphery even at 3 months after surgery (Fig.1A). At 3 and 6 months a stratified squamous epithelium AE5 positive and bearing corneal features occupied the corneal center, where the inflammatory process was absent (Fig.1B). The positive reaction with the AE5 was detected only in the suprabasal layers (Fig.1C).
Conclusions:
Preliminary experiments using scanning electron microscopy of corneas processed immediately after the surgical procedures demonstrated the efficacy of the scrapings in the elimination the corneal epithelium. It is likely that the conjunctival epithelium, while sliding onto the corneal stroma, carried undifferentiated basal cells, and that these cells, interacting with the avascular central corneal stroma, became corneal epithelium cells.The corneal phenotype was confirmed by the reaction of the newly formed epithelium with the antibody AE5.This antibody identifies keratins 3 and 12, which are known to occur only in the corneal epithelium, being absent in the conjunctiva. The absence of AE5 staining of central basal cells suggests their intermediate stage of differentiation. The lacking of corneal epithelium phenotype on the periphery could be explained by the negative effect of the stromal inflammation.
Keywords: cornea: basic science