Fig. 1: High magnification of cone calyceal processes by expansion microscopy.

Photoreceptor mosaics were examined on flat mounts of the retina by classic confocal microscopy (a, c–g, m–p) and by expansion microscopy (b, h–l, q–t). Photoreceptors were immunolabeled for espin 1 (magenta) and prodocadherin 15 (pcd15, green). a–l Immunolabeling of cone photoreceptors visualized in the photoreceptor mosaic as z-projections (a, b), on confocal optical sections from the outer to the inner segment (c–e, h–j) or on 3D reconstructions from different viewpoints (f–g, k–l). m–t Comparison of fluorescence profiles along a single calyceal process, showing the greater resolution of expansion microscopy (r–t) than of classic confocal microscopy (n–p) for espin 1 and Pcd15 immunostaining (numerical data in supplementary data 1). The profile section (yellow line) is shown on the isolated calyceal processes (n, r). Scale bars represent 10 µm in (a) and (b), and 1 µm in (c) to (l) (after division by the 4.5 expansion factor in b, h–l).