Abstract
Abstract: :
Purpose:Ocular surface is made up of three types of epithelium, namely corneal epithelium (CE), corneal limbal epithelium (LE) and conjunctival epithelium (CJE). It is known that in some points these types of epithelium are different from each other and one of the major differences is the vascular system under the epithelium. While under CE there is no vascular system, connective tissue under CJE is vascular rich and under LE a limbal vessel network exists. To elucidate the relationship between the existence of a vascular system under the epithelium and some angiogenesis related factors, we examined CE, LE and CJE in regard to the expression of angiogenesis–related factors. Methods:We used residual tissues of donor eye obtained at PKP surgery (n=3) and made sections including from the central cornea to the limbal conjunctiva. Immunohistochemistry was used to determine protein expression of angiogenesis–related factors (TSP–1, PEDF, endostatin angiostatin, VEGF, Flt–1, KDR and bFGF) in each epithelium. Results:Immunohistochemistry disclosed the presence of TSP–1 in the basal layer of CE but was not expressed in LE or CJE. The expression area of TSP–1 in CE was correspondent to the existence area of Bowman’s layer. PEDF, endostatin, angiostatin VEGF, Flt–1 and bFGF were expressed in each epithelium and there was no difference among three types of epithelium. KDR was not expressed in any epithelium. Conclusions:This study suggests there is a possibility that TSP–1 is one of the key factors regarding the avascularity under CE.
Keywords: cornea: epithelium • neovascularization • immunohistochemistry