Expression of zebrafish CRMP2 from the 12- to 20-somite stages. At the 12-somite stage, CRMP2 is expressed at low levels ubiquitously throughout the embryo in both neural and non-neural tissue (A) as compared to sense controls (C). Slightly higher levels of expression are detected in the anterior portion of the embryo (A) as well as in regions just lateral to, and within, the hindbrain corresponding to the developing trigeminal sensory ganglia (TG/tg) and hindbrain clusters (asterisk, B) respectively. At the15 somite stage CRMP2 continues to be detected in the TG (D and E) and future hindbrain clusters (asterisk, E). CRMP2 is also expressed in cells of the dorsal rostral cluster (drc) of the telencephalon, ventral rostral cluster (vrc) of the diencephalon (D), and Rohon Beard cells (RB) of the neural tube (box in D, enlarged dorsal view in F). The expression pattern of CRMP2 in the TG and RB cells is compared to that of Zn-12, an antibody recognizing both types of cells (G, H, I). By the 20 somite stage CRMP2 is now also detected in the ventral caudal cluster (vcc) of the mesencephalon (J). Expression of CRMP2 in these major clusters and ganglia can be seen in cross-sections (L–N). At the 20-somite stage, expression of CRMP2 overlaps with PlexinA4 expression in the TG (K versus O). All whole-mount embryos are presented anterior to the left. Figures B, E, F, H, I, K and O are de-yolked, dorsal views. Figures L, M, and N are 7 μm sections taken through the regions of the brain as outlined in J and K.

Expression of zebrafish CRMP2 at 22–24 hpf, in comparison with PlexinA4. From 22 hpf, specific expression of CRMP2 is strongly detected in anterior neural structures including the drc, vrc, vcc, TG (A, B), and hindbrain (asterisk A, C). A comparison of CRMP2 and PlexinA4 expression shows overlapping expression in the drc, vcc, hindbrain, and TG (A–C versus D–F). PlexinA4 displays broader expression as it is also expressed in the dorsal diencephalon (ddi), and dorsal mesencephalon (dme). CRMP2 is clearly expressed in the RB cells from a lateral view (G), as compared to Zn-12 staining (H). Figures B, C, E, and F are de-yolked, dorsal views. The vertical double headed arrow denotes the boundaries of the notochord. Dotted white lines in L, M and N represent the boundaries of the zebrafish central nervous system. Abbreviations: drc (dorsal rostral cluster), vrc (ventral rostral cluster), vcc (ventral caudal cluster), RB (Rohon Beard cells), TG or tg (trigeminal ganglion), asterisk (hindbrain or hindbrain clusters).

Expression of zebrafish CRMP2 at 30 hpf and 48 hpf, in comparison with PlexinA4. At 30 hpf, CRMP2 is expressed in the drc, vrc, vcc, TG, RB cells, and the hindbrain (A, A′, B). CRMP2 expression overlaps with PlexinA4 in all of these structures with the exception of RB cells, where Plexin A4 is very weakly expressed. Plexin A4 is also expressed in the dorsal mesencephalon (arrowhead), and dorsal diencephalon (thick arrow) (C, D). By 48 hpf, CRMP2 (E, E′, F) and PlexinA4 (G, G′, H) have a dramatic increase in the amount of expression in the central nervous system. CRMP2 expression becomes more diffuse throughout the entire brain, although it is still localized in some regions of the brain (Fig. 5E, E′, F, sections 5I, 5J, 5K). At 48 hpf, CRMP2 is clearly detected in the developing retinal ganglion layer (E, F and section I). At 48 hpf, CRMP2 is also expressed in the otic vesicle (E, E′), as evident in cross-sections (K). PlexinA4 is also clearly expressed in the otic vesicle (G, G′). Figures B, D, F and H are de-yolked, dorsal views. A′, C′ E′ and G′ are enlargements of staining from just behind the eye of A, C, E and G respectively. Figures I, J, and K are 7 μm sections taken through the regions of the brain as outlined in E.