Time-course of restoration of PKCα + ON bipolar neurons and their synaptic terminals following selective lesion. Tissues were processed for indirect immunofluorescence and imaging after ERG recordings. Retinas were of zebrafish transgenic for sws2:mCherry (in blue cones) and nyx:mYFP (in a subset of bipolar neurons); in this line the mYFP is expressed in a variegated manner (Schroeter et al., 2006), therefore not all of the panels in this figure show the YFP reporter. (A). Control retina displaying characteristic ON-bipolar synaptic terminals within the deep (s4-6) layers of the inner plexiform layer (IPL). (B). Retinal tissue at 3 days post-injury (DPI), demonstrating loss of inner retinal structure, and particularly of PKCα + ON-bipolar neurons. Photoreceptors, including sws2:mCherry + blue cones, are not damaged by the selective lesion. (C–H). Regenerating retinas at 13 (C), 21 (D), 30 (E), and 80 DPI (F). Some features of IPL emerge by 13 DPI (C), but PKCα + ON bipolar axon terminals are not entirely localized to regions that are recognizable as sublaminae s4-6. At 21 and 30 DPI, PKCα + terminals occasionally reach what appear to be the deeper layers of the IPL (D,E). At 80 DPI, PKCα + terminals are found in the deep, ON layers of the IPL (F). ONL, outer nuclear layer; INL, inner nuclear layer; scale bar (in A, applies to all) = 50 μm.
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