FIG. 3.

Late embryonic expression of Foxs1. X-Gal staining of 100-μm vibratome sections of E15.5 (A to C) and E18.5 (D to G) embryos is shown. (A) Foxs1 expression is present in the EGL of the forming cerebellum and in the deep fastigial nucleus (FN). Staining remains strong in sensory division of cranial ganglia (B) as well as in DRG, but at this stage, Foxs1 is also expressed in peripherally located Schwann cells along the ventral ramus of the spinal nerve (C). In the E18.5 embryo, cells just beneath the nasal epithelium (arrows in panel D), in the cartilage primordium of the nasal septum, stain positive for β-galactosidase. At this stage, the retina (ret) is negative for β-galactosidase (D). Expression is evident in the cochlear nucleus (CN) and in Schwann cells of the cochlear (cn) and vestibular (vn) nerves extending from the vestibulocochlear ganglion (VIII) (E) and also in Schwann cells of a branch of the trigeminal nerve (nV) extending toward follicles of vibrissae (fvib) (F). (G) Foxs1 expression has been initiated in the gray matter of the spinal cord (sc).