Fig. 3

Fig. 3

Characteristics of parietopsin-expressing photoreceptor cells in the lamprey pineal organ. A–C Fluorescence triple staining images showing parietopsin (A, yellow, arrowheads show outer segments), β-arrestin (B, cyan, whole cell), and ganglion cells labeled by retrograde tracing with neurobiotin (B, magenta). The white arrow shows the contact between the parietopsin photoreceptor cells and ganglion cells (C). The dotted trace indicates the outline of the pineal organ. D–G Fluorescence quadruple staining images showing localization of β-arrestin (D, white), VGLUT (E, cyan), parietopsin (F, yellow), and parapinopsin (F, magenta). Landmarks with broken line indicate outlines of photoreceptor cells. The yellow and magenta arrowheads in F and G show the outer segments of parietopsin- and parapinopsin-expressing photoreceptor cells, respectively. Both parapinopsin- and parietopsin-expressing photoreceptor cells employ glutamate as a neurotransmitter. Scale bar = 20 μm (A), 10 μm (D)