Expression of slits and robos in the developing chick inner ear from stage 14 (E2) to stage 32 (E7.5). In situ hybridizations on frozen sections in the horizontal (A–P) or transverse plane (Q–AA). Some sections (I,M,N,P,Q,V,Z) are double labeled with a neurofilament antibody. Prosensory regions are identified by Bmp4 expression (P,V). A–E: Stage 14 (A–C) or stage 15 (D,E), A,C and D,E are serial sections. F–J: Stage 17, F–H are serial sections. K–P: Stage 23, L,M and N,P are serial sections. Q–V: Stage 27, S–V are serial sections. W–AA: Stage 32, W,X,Z and Y,AA are serial sections. Scale Bars, 100µm. Orientation: A, anterior; D, dorsal; M, medial. Abbreviations: AC, anterior crista; AG, auditory ganglion; BP, basilar papilla; E, embryonic day; LM, lagenar macula; HB, hindbrain; P, posterior Bmp4-positive focus; SAG, statoacoustic ganglion; SM, saccular macula; VG, vestibular ganglion.