Graciarena et al., 2014 - Dynamics of axonal regeneration in adult and aging zebrafish reveal the promoting effect of a first lesion. Proceedings of the National Academy of Sciences of the United States of America   111(4):1610-1615 Full text @ Proc. Natl. Acad. Sci. USA

Fig. 1

Patterns of PLL nerve regeneration. (A–D) Nerve regeneration in a mosaic fish in which most PLL neurons are labeled. Nerve branches on somites 14–25 before the nerve was cut (A), 2 d later (B), 3 d later (C), and 6 d later (D). Wallerian degeneration is evident in B and C. Regeneration has reached somite 13, just left of panel B, after 2 d and was complete including the caudal lines after 6 d. Arrows in A point to slight departures from the usual pattern; all departures were faithfully reproduced by the regenerating axons (arrows in D). Asterisks in D point to differences between the original and the regenerated patterns. The cut was done at the level of somite 2 on a 1.5-mpf mosaic fish derived from a wild-type blastula transplanted with cells from a nbt:dsred donor blastula. Most or all PLL neurons were fluorescent on the left side of this particular mosaic fish. (Scale bar, 500 μm.)

Fig. 4

Involvement of Schwann cells in axonal regeneration. (A) Three days after nerve cut in 1-mpf fishes, the axons have fully degenerated (double-headed arrow), but Schwann cells (arrowheads) are not noticeably affected posterior to the leading growth cones (arrows). (B) During regeneration, the leading growth cone (arrows) and neurite (double arrow) are closely apposed to Schwann cells (arrowheads). (C) 2 d after nerve ablation, Schwann cells are still absent from the exposed region (double-headed arrow), yet the growth cones of regenerating neurites (arrowheads) have crossed the glial gap. Regenerating neurites are notably defasciculated over the ablated region (arrows). (Scale bars, 50 μm for A and B; 100 μm for C.)

Fig. 5

Regeneration after extended nerve ablation. (A) In nbt-dsred; Sox10-gfp fishes, Schwann cells (arrowheads) extend over the ablated region (double-headed arrow) along the massively defasciculated regenerated axons. (B and C) Nerve ablation over 2–3 somites (double-headed arrows) does not prevent axonal regeneration but results in many axons following alternative courses over the ablated stretches (arrowheads). (Scale bars, 200 μm.)

Fig. S1

Posterior lateral line nerve regeneration. (A, A′) Stitch reinnervation in 6-mo postfertilization fishes, 1 wk after nerve cut. The overall pattern of the original nerve branches (A) is reproduced by the regenerating axons (A′). Minor abnormalities in the path of nerve branches (B, arrow) are also reproduced after regeneration (B′, arrow). Small changes in the pattern of innervation within the stitch can be observed (B′, asterisks). More extensive departures from the normal branch pattern are occasionally observed in the more posterior region (C) and are also reproduced after regeneration (C′). (Scale bars, 300 μm.)

Fig. S2

Involvement of Schwann cells in axonal regeneration. (A) Three days after nerve cut in 1-mo postfertilization fishes, the axons have fully degenerated (double-headed arrow), but Schwann cells (arrowheads) are not noticeably affected posterior to the leading growth cones (arrows). (B) During regeneration, the leading growth cone (arrows) and neurite (double arrow) are closely apposed to Schwann cells (arrowheads). (C) 2 d after nerve ablation, Schwann cells are still absent from the exposed region (double-headed arrow), yet the growth cones of regenerating neurites (arrowheads) have crossed the glial gap. Regenerating neurites are notably defasciculated over the ablated region (arrows). (D) Reinnervation may proceed from one neuromast to the next, either anteriorly (arrows) or posteriorly (arrowheads). (E-E3) Regenerating axons may grow ventrally and then dorsally again to join the major nerve path (arrows in E3).

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This image is the copyrighted work of the attributed author or publisher, and ZFIN has permission only to display this image to its users. Additional permissions should be obtained from the applicable author or publisher of the image. Full text @ Proc. Natl. Acad. Sci. USA