THE PERMEABILITY OF THE RABBIT CILIARY EPITHELIUM TO HORSERADISH PEROXIDASE IN EXPERIMENTAL UVEITIS An electron microscopic study

Abstract

Experimental uveitis has been produced in two groups of albino rabbits by a single intravitreal injection of antigen. The animals in group I were immunized by injection of 10 mg of human serum albumin, whereas those belonging to group I1 received 50 mg of the same antigen. To study the blood-aqueous barrier to proteins in the ciliary body of these eyes, horseradish peroxidase has been used as a cytochemical tracer by electron microscopy. The tracer was injected intravenously at different time intervals (1-30 min) before enucleation.In group I, in regions of inflammatory cell infiltration in the ciliary processes, peroxidase reaction product was observed in the lateral intercellular spaces of the superficial epithelium, in the internal limiting membrane, and in the posterior chamber, as evidence of breakdown of the epithelial diffusion barrier. In areas showing moderate or no inflammatory cell infiltration, the diffusion barrier to peroxidase was found intact, although the epithelium displayed marked morphological alterations.In the more heavy inflamed eyes belonging to group 11, necrosis of the ciliary epithelium and thrombosis of the ciliary vessels were prominent. K e y words: uveitis, experimental -ciliary body -aqueous humorproteins -peroxidase -rabbits -electron microscopy.

Electron Microscopic Studies on the Blood‐aqueous Barrier of Prostaglandin‐treated Rabbit Eyes

“…2 Smelser 1969, Pedersen 1974. Evidence indicating that PGs are involved in these reactions has been presented (Eakins et al 1972, Neufeld, Jampol & Sears 1972.…”

A Light and Electron Microscopic Study of the Permeability of the Rabbit Iris Vessels to Horseradish Peroxidase in Experimental Uveitis

“…It is assumed that the source of this is the ciliary body. Thus, in the same eyes rapid leakage of peroxidase through the ciliary epithelium has been demonstrated in previous studies (Pedersen 1973(Pedersen , 1974. Peroxidase that has reached the anterior chamber will be able to enter the iris stroma via the anterior surface of the iris that has no continuous cellular lining.…”

“…In experimental uveitis of the present type, the main inflammatory reaction takes place in the ciliary body. This has been discussed previously (Pedersen 1974). When, however, the inflammation becomes intense, the reaction in the iris will also be prominent.…”

“…Iris tissue was obtained from the same eyes that were used in a previous study of the ciliary epithelium (Pedersen 1974).…”

“…The cytochemical controls, as well as the control for histamine and serotonin liberation induced by the peroxidase injection itself, were the same as described previously (Pedersen 1974).…”