Cas adaptor proteins are essential for cranial nerve development. (a–f) Whole-mount immunostaining of Control (a,c,e) and Wnt1Cre; TcKO embryos (b,d,f) at e11.5 (a,b) and e12.5 (c–f). The central projections of the vagal nerve (VN) are severely defasciculated in Wnt1Cre; TcKO embryos (b, yellow arrowhead). The ophthalmic branch trigeminal nerve appears underbranched in Wnt1Cre; TcKO (d) embryos compared to controls (c). (e–f) Higher magnification view of white boxes in c and d reveals exuberant defasciculation of the maxillary branch of the trigeminal nerve in Wnt1Cre; TcKO embryos (f, white arrows). OB: Ophthalmic Branch; MxB: Maxillary Branch; MdB: Mandibular Branch. n = 6, 100% penetrance. Scale bars: 200 μm for (a–d); 100 μm for (e,f).