Fig. 1.

Expression of opsin in photoreceptors and development of polarity in ARPE-19 in retina neurons cocultured with differentiated RPE cells. Phase (A) and fluorescence (B–F) photomicrographs of retina neurons seeded on ARPE-19 epithelial cells, after 8 days in coculture. Photoreceptor cells (white arrows in A,B) were labeled with Rho4D2 monoclonal antibody (B) for immunochemical detection of opsin. Photoreceptors seeded on epithelial cells recognized epithelial apical surfaces and expressed opsin (B). Confocal images of RPE cells double stained with the apical marker CD147 (C,E) and TO-PRO3 (D,F), to label cell nuclei. C,D: x-y sections at z 5 100 showing that CD147 was widely and selectively expressed in RPE cell membranes exposed to the culture media (C). x-z section obtained at the level indicated by the white lines in (E,F). Note that the apical marker CD147 was absent from RPE membranes contacting the substrata (E). Scale bars = 10 µm.