Fig. 6. GDNF is required for target innervation of ciliary ganglion neurons. (A,B) An E7 chick ciliary ganglion stained with Toluidine Blue (A) or anti-Ret antibody (B). The ciliary ganglion is located near the optic nerve and extends its axons in the distal direction. The majority of neurons in the ciliary ganglion at this stage are Ret positive. (C,D) DiI labeling of ciliary ganglion pioneer axons in an E8 chick embryo that was grown for 4 days in vivo in the absence (C) or presence (D) of a function-blocking antibody to GDNF. Growing axons and branches usually seen in control embryos (arrowheads in C) were totally suppressed in embryos that were grown with the exogenously applied GDNF antibody (D). (E,F) Transverse sections of part of the head of chick embryos grown in the presence of the GDNF antibody. (E) Several neurons in the ciliary ganglion exhibit shrinkage of their cell body (arrowheads). (F) Vestibular ganglion axons (arrows) show normal innervation patterns and extend their processes into the vestibular epithelium. Scale bar (shown in A): A,B, 200 µm; C,D, 400 µm; E, 40 µm; F, 250 µm. CG, ciliary ganglion; VG, vestibular ganglion; SE, sensory epithelium.
