Fig. 6

Retinal pigment epithelial organoids acquired pigmentation in the presence of T3 hormone. A (a) Phase contrast microscopy images of CB30-derived mzOPCs cultured for 30 days showing neuroretinal areas (NRs) surrounded by RPE cells. Scale bar: 250 µm. (b–d) Bright-field images of CB30-derived RPE organoids cultured in suspension for 120 days in the presence of T3 from day 90. Scale bars: 3 mm in b; 1 mm in c; 25 µm in d. B Hematoxylin and eosin staining of RPE organoid paraffin sections. The dashed square in b indicates the magnification area shown in c. Scale bars: 100 µm in b; 50 µm in a, c, d. C (a) Immunostaining of a paraffin section with antibodies against MITF and COL IV (B-a and C-a images correspond to the same sections). Confocal immunofluorescence images of the RPE organoid surface with the following RPE-specific markers: RPE65, MITF, ZO-1, BEST (bestrophin-1), and CD59 (b-d). Tra-1-60 was used to detect undifferentiated cells. Scale bars: 50 µm in a; 25 µm in b, d; 7.5 µm in c. Nuclei were stained with DAPI