LAMININ SUBTYPE DISTRIBUTION IN THE HUMAN CILIARY BODY

Purpose. Laminin is a family of heterotrimeric molecules each consisti ng of a heavy chain (A or M chain), and two light chains (B1, B2, or S chains). In this study the distribution of these chains was determine d in human ciliary body.Method. Tissue slices from five postmortem eye s were incubated with monoclonal antibodies against the chains and wit h a fluorescent secondary antibody. After the tissues were embedded in Spurr's resin, 1-mu m thick sections were obtained. Results. Uniform staining with A, S, and B2 laminin chains was observed in basement mem brane surrounding muscle bundles. Inside the bundles, the basement mem brane around individual fibers was evenly stained by S and B2; however , only some fibers had A-chain immunoreactivity. The basement membrane of blood vessels was also stained with A, S, and B2. Stromal connecti ve tissue was not stained. Ciliary pigmented epithelium basement membr ane was brightly stained with A, S, B1, and B2; nonpigmented epitheliu m basement membrane demonstrated A, S, and B2 immunoreactivity, but no t B1 immunoreactivity, Adjacent to the nerves, M, S, B1, and B2 immuno reactivity was detected. Conclusion. The results indicate that A-S-B2 laminin is present in the basement membranes associated with smooth mu scle bundles, blood vessels, and the nonpigmented and pigmented epithe lia. A-B1-B2 laminin is also found in the pigmented epithelium basemen t membrane. M-B1-B2 and M-S-B2 are found in association with nerve tis sue. This heterogeneity in the basement membranes of the ciliary body suggests that they mediate different cellular functions.