97th DOG Annual Meeting 1999

K685

NEW FINDINGS IN THE STRUCTURAL COMPOSITION OF ASTEROID BODIES IN ASTEROID HYALOSIS

J. Winkler, H. Lünsdorf*, M. Asiyo-Vogel, H. Laqua

Introduction: The seldom encountered clinical picture of asteroid hyalosis is characterised by glistening particles suspended in the vitreous body. Little is known about the formation and chemical composition of these asteroid bodies. In these investigations we take a closer look into the physico-chemical nature of asteroid particles.

Methods: I. Element specific investigations with transmission electron microscopy (TEM) in conjunction with electron spectroscopic imaging. II. Determination of the surface charge of asteroid bodies in TEM through the use of a cationic gold marker. III. Complete degradation of the cristalline structure by a chelator agent, documented in TEM.

Results: Electron spectroscopic investigations showed that besides calcium and phosphorus, sulphur and oxygen are also structural components of asteroid bodies. Contrary to other studies up to date, the application of cationic gold marker revealed no negative charge distribution on the crystalline surface of the asteroid particles. Negative groups were however documented in the direct surrounding of the bodies. The application of various chelators for bivalent cations resulted in rapid disintegration of the asteroid particles.

Conclusion: The absence of negative surface charge in correlation to the observed none sensitivity to osmium or lead citrate staining also indicates that the lamella structure of the asteroid body does not consist mainly of acidic phospholipids as has been assumed to date. The susceptibility of the calcium to specific chelators documents the significance of calcium ions for the structural integrity of asteroid particles.

Universitäts-Augenklinik, Ratzeburger Allee 160, D-23538 Lübeck
*Gesellschaft für biotechnologische Forschung, Braunschweig


Back