Figure 5. Immunohistochemistry of porcine arteriovenous crossings. Immunohistochemical staining of serial paraffin sections of porcine retinal arteriovenous crossing sites using antibodies raised against ACTA2 (A, C, E, and G) and GFAP (B, D, F, and H). Vicinal sections are compared. While the antibody raised against GFAP stains astrocytes (and some Müller cells) in the nervous tissue surrounding the vessel, the antibody raised against vascular smooth muscle ACTA2 stains the compact layer of the vessel wall that is intensely stained by aniline blue in the trichrome staining. The layers of the vascular wall that are stained by the antibody raised against ACTA2 are touching but not fusing. There is no space left for cells expressing GFAP between the two vessels at the center of the crossing. Note that the astrocytes show a much higher density around the vessels. A and B show the same arterial overcrossing as in Figure 4D.