||Fig. 4. In intact embryos, tau knockdown reduced peripheral nerve development. Embryos were injected at the two-cell stage with tau antisense morpholino
oligonucleotide (MO) and immunostained at st. 37/38 in whole-mount for tau, to visualize effects of the MO on tau expression (A), and for peripherin (B1–2,
C1–2), to visualize effects on peripheral nerve development. (A) View in the horizontal plane illustrating normal tau immunostaining within the brain (arrowhead
1), cranial peripheral nerves (e.g. arrowhead 2) and spinal cord (arrowhead 3) on the uninjected side of the embryo (left of the dotted line) and reduced
tau immunostaining on the side descended from the blastomere injected with MO (right of the dotted line). Rostral is toward the top. The image represents a
maximal intensity projection stack of 33 confocal laser-scanning microscopy sections (objective: 109; NA 0.5) with a voxel size of 2.5 9 2.5 9 6.4 lm. (B1
and 2) Parasagittal views through trunk level somites illustrating diminished robustness of peripheral motor nerve development (arrowheads) on the injected
(B2) vs. uninjected (B1) side. Images represent a single optical section (109; NA 0.5) taken at comparable depths through the somites; voxel size is
1.8 9 1.8 9 5.1 lm. (C1 and 2) Parasagittal views through the head illustrating diminished robustness of cranial nerve development on the injected (C2) vs.
uninjected (C1) side. Rostral is toward the right. Images represent a maximal intensity projection stack of 15 confocal laser-scanning microscopy sections (109;
NA 0.5) with a voxel size of 1.6 9 1.6 9 3.1 lm. Scale bars: 100 lm for all panels; (B1 and 2) are at the same magnification, as are (C1 and 2). (D) Average
lengths ( SEM) of cranial and spinal peripheral nerves of tau and control MO-injected animals immunostained for peripherin at st. 37/38 (N = 3). **Significantly
different from controls, as determined by t-test, P < 0.01. Abbreviations: II, optic nerve; IX, glossopharyngeal nerve; Vmd, mandibular branch of the
trigeminal nerve; Vop, ophthalmic branch of the trigeminal nerve; VII, facial nerve; SN, spinal motor nerves; X, vagus nerve.