(a) Diagram of rod phototransduction pathway in vivo. (b) Three-dimensional RCs still maintained their structural organization in W27. (c–i) Photoreceptors within the RCs showed expression of phototransduction proteins with the appropriate cellular distributions (OS: putative developing outer segments). (j–l) Perforated-patch electrophysiological recordings from CB-iPSC6.2-derived photoreceptors, showing the flash-triggered responses (single trial) from two light-sensitive cells (j), the lack of flash response from one light-insensitive cell (k) and collected data from 13 cells (l). Cells were voltage clamped at −50 mV. Inward current is negative. Flash (indicated by arrow) was 40 ms in duration and 2.46 × 105 μW cm−2 in intensity (white light from a mercury arc lamp). In l, open circles indicate individual cells, solid circles indicate mean values and error bars indicate s.d. Scale bars, 50 μm (b,c); 5 μm (d–i).