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. 2017 Dec;187(12):2841–2857. doi: 10.1016/j.ajpath.2017.08.025

Figure 2.

Figure 2

Elastic fiber degradation and loss of smooth muscle cells (SMCs) in choroidal vessels of both Tg44 and human polypoidal choroidal vasculopathy (PCV). A: Van Gieson staining showed the loss of internal elastic laminae (IELs) of a choroidal artery in Tg44 PCV lesions. Black brackets and black arrows in Tg44 indicated missing and partial loss of IEL, respectively. Green arrows indicated normal IEL in WT and Tg33. B: Transmission electron microscopy image showed a collapsed artery in Tg44 PCV lesion. Endothelial cell degeneration (red arrows), SMC atrophy (asterisks), and degeneration of both IEL (blue arrow) and external elastic layer (EEL; yellow arrows) were evident. Part of the IELs was missing (red bracket). The EEL (yellow arrows) drifted away through the tunica media and also merged with IEL (blue arrow). Tg33 (red arrowheads) and wild type (WT; orange arrows) had normal IEL. EEL (green arrow) and endothelial cells (black arrows) were normal in WT. C: Van Gieson staining showed stretches of IELs of a collapsed choroidal vessel in human PCV lesion were missing (red brackets), degenerating (black bracket), or broken (red arrows). IEL was normal in a control artery (black arrows). D and E: Immunostaining of α-smooth muscle actin (α-SMA) in human (D) and mouse (E) PCV lesions. The choroidal medial SMCs were partially lost in the bottom left panel (white brackets), and were completely lost in the bottom right panel (D). SMC loss (white brackets) and degeneration (yellow bracket) in choroidal vessel wall of Tg44 were shown (E). SMCs were intact in WT and Tg33. Nuclei were counterstained with DAPI (blue). F: Western blot analysis on retinal pigment epithelium/choroid lysates showed that the α-SMA level was significantly decreased in Tg44 when compared with both Tg33 and WT controls. Glyceraldehyde-3-phosphate dehydrogenase (Gapdh) was included as the loading control. Statistical significance was assessed using one-way analysis of variance with post-hoc Tukey test. Data are expressed as means ± SEM (F). n = 4 (F). ∗P < 0.05. Scale bars: 10 μm (A and E); 1 μm (B); 20 μm (C and D).