Fig. 6

Localization of Zash-1b transcripts in the wild-type 24-hr CNS. Thick sections of whole mount in situ hybridized embryos (as in Fig. 5) were observed and photographed under DIC optics. Sections are of same regions illustrated in Fig. 4. (A) Longitudinal section of head showing region from anterior tip of head to cerebellum (eye and lateral head removed). (B) Longitudinal section of hindbrain. Symbols: arrowheads, approximate rhombomere borders; arrows, fan- shaped expression zone in basal plate near rhombomere borders; filled triangles, ventral expression zone near floor plate. Outline of otocyst is shown as dotted line. (C) Transverse section of anterior midbrain. (D-F) Transverse sections of rhombomeres 1, 4, and 7, respectively. Symbols: arrows, fan-shaped expression zones in basal palate; arrowheads, border of this zone at the boundary between alar and basal plates; filled triangles, as in (B). (G) Transverse section of midtrunk spinal cord, one end of the double-headed arrows indicates highest level of transcripts in intermediate zone. Planes of transverse sections (C-F) are indicated by the double-headed arrows in (A) and (B). Plane of transverse section in Fig. 9C is indicated in (A) by a double-headed arrow without an accompanying letter. Abbreviations as in Figs. 3 and 4. Scale bars, 100 μm, magnification of (A-C) is identical, and of (D-G) is identical.