Histoautoradiographic and biochemical studies on human and monkey trabecular meshwork and ciliary body in short-term explant culture.

Explants of two types of chamber angle tissue derived from five human autopsy eyes and five freshly enucleated monkey eyes were kept under tissue culture conditions for 1-3 days and then incubated with labelled 14C-glucosamine for 40-48 h. In all specimens an intense labelling was seen histoautoradiographically within the area of the trabecular meshwork, especially in the cribriform layer and the outer wall of Schlemm's canal. Large quantities of silver grains were also found at the tips of the ciliary processes where the nonpigmented epithelium showed the most intense labelling. Measuring the total radioactivity of the two types of specimens in the tissue-localized and the medium-released glycosaminoglycans (GAGs), we found that the type 1 specimens containing only trabecular meshwork work and corneosclera "excrete" relatively more GAGs into the medium than the type 2 specimens consisting of corneosclera, trabecular meshwork and ciliary body. Biochemical analysis of these GAGs revealed that 57%-70% of the tissue GAGs were hyaluronic acid, 16%-33% heparan sulphate and 12%-22% various types of chondroitin sulphate. The findings show that both the ciliary epithelium and the trabecular meshwork possesses the ability to synthesize large amounts of GAGs, probably in the form of proteoglycans. The differences between the in vitro behaviour of type 1 and type 2 specimens indicate a functional interrelationship between the ciliary body and the trabecular meshwork, at least with regard to the GAG metabolism.