Figure 13

Ciliary muscle but not trabecular meshwork displays smooth muscle features resembling those of distal aqueous drainage tract wall. Immunohistochemistry (IHC) showing regions where filamentous actin (F-actin; red) and smooth muscle epitopes (alpha smooth muscle actin (ASMA; b), caldesmon (c) or calponin (d; all green; see insets)) co-localize (yellow; b–d). Co-localization between F-actin and smooth muscle epitopes is seen in ciliary muscle (CM; yellow), which is smooth muscle, but not in trabecular meshwork (TM; thin red band next to Schlemm’s canal (SC)). (a) H&E staining of a C57BL/6 mouse eye illustrates the orientation of proximal aqueous drainage tissue¹⁶. Dashed box: iridocorneal angle drainage tissue region that was the focus of subsequent IHC images (b–d; Balb/c). Lack of pigment in albino Balb/c mice allowed unbiased analysis of fluorescence labeling across the otherwise pigmented drainage tissues. (b–d) Dashed line: outline of SC. F-actin was present in the TM (red) and CM, but F-actin co-localization (yellow) with ASMA (b), caldesmon (c) and calponin (d) was a prominent feature of CM but not TM. Insets: 3X magnification of regions indicated by asterisks illustrating prominent F-actin co-localization with smooth muscle epitopes in CM (yellow) but not TM (red). Bar = 20 μm.