Fig. 6. EphA receptor expression profiles of retrogradely-labeled areas in IO. (A,E,I,M,Q) DiI insertion sites (red star) in the cerebellum. (B,F,J,N,R) Retrogradely labeled neurons in the contralateral IO. Dashed lines indicate ventral outlines of the brainstem. Dorsal is at the top. Vertical lines indicate midline. (C,D,G,H,K,L,O,P,S,T) EphA3 and EphA5 expression detected by RNA in situ hybridization in the same and adjacent coronal sections through the IO (arrowheads). Scale bar, 500 µm. (U) A diagram indicating the positions of coronal planes of the sections. (A-D) The caudal domain B is innervated by axons from the medial IO, where both EphA3 and EphA5 are expressed (Area Ml). (E-H) The rostral domain B receives axons from the caudo-intermediate IO, where no EphA3, but strong EphA5 expression is detected (Area Ic). EphA6 is also expressed in this area (data not shown). (I-L) The middle region of domain C receives axons from the rostro-intermediate IO, where no EphA3 and moderate EphA5 expression is detected (Area Ir). EphA6 expression was not detected in this area (data not shown). (M-T) The rostral parts of domains C and A receive axons from the lateral IO, where both EphA3 and EphA5 are not expressed (Area L).