Fig. 3.

Fbxw7 mutant SCs display branched 3D morphology. Dissociated SC/DRG co-cultures from control (a) and Dhh^cre(+):Fbxw7^fl/fl (b, c) mouse embryos indicate that WT MBP(+) SCs are bipolar (a), whereas mutant SCs can assume a multipolar morphology (b) sometimes with highly branched processes (c). These phenotypes did not occur in the control cultures (d; p = 0.0099, unpaired t-test with Welch’s correction). Data are quantified per 490.88 mm² and represent two technical replicate cultures from each of three independent mouse embryos per genotype. Scale bar is 20 μm. Serial block-face scanning electron microscopy (SBF-SEM) images of a Dhh^cre(+):Fbxw7^fl/fl nerve at P150 (e–h). A mutant SC extends a thin cytoplasmic process between an unmyelinated axon (marked by a) to a myelinated axon (marked by m) (e; white box denotes the area shown in (f); cyan asterisk is for reference). In some sections we see that the process is distinct and does not touch the membrane around the myelinated axon (f; yellow dotted line denotes cell membranes; cyan asterisk for reference). However, in other sections it is clear that these two axons are joined by continuous cytoplasm (g, h). SBF-SEM images shown here are stills from Supplementary Movie 1. Error bars depict S.D.