Localization of Elastic Fibers and Elastin mRNA in the Uvea of Chick Embryo

Abstract

The distribution of elastic fibers and elastin mRNA was studied in the uvea of 19-day-old chick embryos by light and electron microscopy and in situ hybridization techniques using a ³⁵S-labeled RNA probe. Light and electron microscopic examination revealed that elastic fibers were present in the uveal portion of the ciliary body, but not in the posterior choroid. Electron microscopically, elastic fibers were also found in Bruch’s membrane. Abundant amounts of elastin mRNA were strictly localized in the fibroblasts in the uveal portion of the ciliary body, and no elastin mRNA was found in any of the cells in the posterior choroid by in situ hybridization. Cultured uveal tissue obtained from the ciliary body was found to produce large amounts of tropoelastin as compared with cultured posterior choroid. Using V8 protease peptide mapping and Northern blot analysis, the tropoelastin and its mRNA produced by the ciliary body were identical to those produced by the smooth muscle cells in the aorta. The results suggest that elastin is synthesized in the ciliary body, acting as a supporting substance in this area.

The Retinal Pigment Epithelium in Visual Function

“…The elastin layer is connected with the ciliary epithelium (318). During the development of the chick embryo, the expression of elastin could only be detected in the ciliary epithelium, which indicates that a part of Bruch's membrane is possibly not only built by the RPE/choriocapillaris complex (606).…”

The choroid-sclera interface: An ultrastructural study

“…While it is commonly accepted that a decrease in elastic matrix properties takes place during aging [ 54 ], and this holds also true for the choroid [ 55 ], only minor changes in biomechanics have been described in aged human eyes [ 56 ]. Elastin has been detected in avian eyes during ciliary body development but not in the choroid [ 57 ], was not observed in this study, but has been described at the ultrastructural level in adult chick eyes [ 29 ]. Whether this difference is age-related, or associated with topographical differences in locations with particularly demanding mechanics, remains unexplored [ 58 , 59 ].…”