Fig 8

The PCP pathway directs A-P axon guidance of Mauthner cells.

A-B) Wild type hindbrain with α-3A10 labeling Mauthner somas and axons. Mauthner axons grow posteriorly, towards the bottom of the image. All images and quantification in figure are from 30 hpf embryos. B) Two representative examples of hoxb1a::fzd3aΔC-GFP transgenic hindbrains with Mauthner somas and axons labeled with α-3A10. Yellow arrowheads indicate axons from left Mauthners and red arrows indicate axons from right Mauthners. In top panels, the left axon grows correctly posteriorly while the right axon grows incorrectly towards the anterior, and in bottom panels, both axons grow incorrectly towards the anterior. Scale bars = 20 μM, Z-projection. C) Quantification of Mauthner axon phenotypes in hoxb1a::fzd3aΔC positive (n = 18) and celsr3^-/-;celsr2^-/- (n = 19) embryos. D,E) Sibling (D) and celsr3^-/-;celsr2^-/- (E) embryos with hoxb1a in situ (magenta) labeling hindbrain rhombomere 4 and nefma in situ (green) labeling reticulospinal neurons, including Mauthner cells (arrowheads). Scale bars = 20 μM, Z-projection. F,G) Mauthner soma and axons are labeled with α-3A10 in siblings (F) and celsr3^-/-;celsr2^-/- (G) embryos. Yellow arrowheads indicate axon from left Mauthner growing correctly towards the spinal cord but displaced laterally. Red arrowheads indicate axon from right Mauthner growing incorrectly towards the anterior. Dotted lines indicate midline and encircle developing ears, for reference. Scale bars = 20 μM, Z-projection.