Figure 5.

Ultrastructure analysis of photoreceptor cells with improved outer segment formation

(A) Immunohistochemical image of RHODOPSIN+ (cyan) OS regions in ALT maintained photoreceptors.

(B) Image showing the localization of α-TUBULIN+ axonemes (cyan) and PHPR2+ OSs (pink) in ALT-cultured photoreceptors.

(C–E) TEM micrographs of 26-week hPSC-derived photoreceptors cultured in ALT +DHA, showing the abundance of OSs (C). High magnification image of inset from C, showing the morphology of disc membranes (D). High magnification image of inset from D, showing stacked disc membranes (E).

(F and G) Transverse TEM section through one OS (F). High magnification image of inset from (F), showing organized and stacked membranous discs (G).

(H–K) 3view serial 3D reconstruction of the ONL region of an ALT +DHA cultured retinal organoid. The photoreceptor ISs (green), CC (blue), and OSs (pink) were pseudo-colored.

Scale bars, 0.5 μm (E and G), 1 μm (F), 2 μm (D),10 μm (A–C). IS, inner segment; CC, connecting cilium; ONL, outer nuclear layer; OS, outer segment.