CAPILLARIES IN THE EPITHELIUM OF PTERYGIUM

Aim-To present new morphological observations of intraepithelial capil laries in pterygium and to provide some explanations for this phenomen on. Methods-The ultrastructural features of pterygia from 26 patients were examined. Surgically excised tissue was processed for conventiona l light and transmission electron microscopy. Results-Individual capil laries within the epithelium of the anterior half towards the head of pterygia were identified in 11 specimens out of 26 pterygia examined ( 42.3%). The perivascular connective tissue of the intraepithelial capi llaries contained fibroblasts, collagen fibrils, and elastin-like mate rial. Epithelial cells surrounding these capillaries showed defects in the basal lamina in contrast with the continuous basal lamina of the endothelium. In the intercellular space of the epithelium an amorphous substance, occasional fibroblast processes, and collagen fibrils were frequently observed. Conclusion-Capillaries in the epithelium of pter ygia are rare, but not exceptional. The ingrowth of these vessels from the stroma into the epithelium can be interpreted as a reaction to hy poxia or deficiency of any other substance transported via the bloodst ream. Apparently, the perivascular connective tissue can be used by in growing fibroblasts as a migration pathway. The migrating fibroblasts appear to use the defects of the epithelial basal lamina (whether part ially or complete) in order to reach the intercellular space. It is po ssible that collagen fibrils in the epithelial intercellular space hav e been laid down by fibroblasts which contribute to the pathological d edifferentiation of the conjunctival epithelium.