Figure 6

Sections of trunk and hindbrain regions of stage HH 14/15 embryos. A-F: zic1 expression by in situ hybridization. zic1 is not expressed in the posterior neural tube (A, B). More rostrally, it is expressed in the dorsal neural tube and in the dorsal portion of recently formed somites (arrow) (C). zic1 expression continues in the dorsal neural tube, dermomyotome (arrow heads), and sclerotome (asterisks) (D, E) and in the dorsal hindbrain (F). G-L: zic2 expression. zic2 is expressed throughout the dorsal/ventral axis of the neural tube in the tail (G). Rostral to the tail region, zic2 expression is restricted to the dorsal portion of the trunk neural tube (H-K). zic2 is expressed in the dermomyotome and sclerotome of rostral somites (K; arrow head and asterisk, respectively). It is expressed in the dorsal hindbrain and in the periotic mesoderm (L). M-R: zic3 expression. zic3 is expressed in the presomitic mesoderm (M, N). It is not expressed in epithelial somites (O) and only further rostrally in more mature somites in the sclerotome (P, Q; asterisks) and in the dermomyotome (Q; arrow head). zic3 is expressed in the dorsal neural tube of the mid- and anterior trunk (P, Q) and in the dorsal hindbrain (R). S-X: zic4 is not expressed in the trunk or hindbrain of stage 14/15 embryos. PSM: presomitic mesoderm; ES: epithelial somite; DS: dissociating somite; POM: periotic mesoderm; arrowheads: dermomyotome; asterisks: sclerotome.