Predominant expression of aquaporin 4 (AQP4, green) at Muller glial cells in retinas of different species (magnification ×40). ILM, inner limiting membrane (arrow); GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; OPL, outer plexiform layer; ONL, outer nuclear layer; OLM, outer limiting membrane (arrowhead); POS, photoreceptor outer segments. (A) mouse; (B) rat; (C) guinea pig; (D) horse; (E) cow; (F) sheep; (G) deer; (H) pig; (I) cat; (J) dog; (K) pigeon; (L) chicken; (M) pheasant; (N) sturgeon; (O) char. Cell nuclei: blue ((4′,6-diamidino-2-phenylindole) DAPI).