Central and peripheral projections of lateralis afferent neurons. (A) GFP-positive peripheral projections in the HGn39D transgenic zebrafish line. Three afferent neurons projecting to a neuromast are depicted. (B) Neuromast innervation in a HuC:Kaede and islet1:gfp double-transgenic larva after Kaede photoconversion. Green neurons are GFP positive, red neurons are Kaede positive and yellow neurons are GFP/Kaede positive. Neuromasts are innervated by both red and yellow neurons. Arrowheads indicate the neuromasts. Dashed lines delimit the spinal cord. (C) Soma of a single TdTomato-positive afferent neuron in a GFP-positive posterior ganglion of an HGn39D transgenic fish. The soma expressing TdTomato is localized in the posterior lateral line ganglion. (D) Central projection of a single TdTomato-labeled afferent neuron. Anterior is to the left and posterior to the right. (E,F) Peripheral projections of a single TdTomato-labeled afferent neuron at two different time frames (10-minute interval). The arrow indicates a bulged extremity, whereas the arrowheads indicate thin and mobile neurites. (G,H) Anti-Ribeye B immunostaining. The formation of ribbon synapses between the afferent neuron (red) and the hair cells (green) is visualized by the presence of the Ribeye B protein (cyan). Arrowheads indicate (G) a thin neurite that does not contact a hair cell, and (H) bulged neurites containing the Ribeye B protein. (I) The average number of neurites present at each time point for wild-type (wt) and tmie mutant fish. Error bars represent the s.e.m. Wild type, n=6; tmie, n=6. Scale bars: 10 μm in A,G,H; 20 μm in B-D; 5 μm in E,F.
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