Expression of Raldh1. In situ hybridisation was performed on wholemount embryos with DIG- or fluorescein-labelled riboprobes. Unless otherwise stated, rostral is top, in views of the dorsal embryo, and to the right in lateral views. Abbreviations: midbrain (mb), hindbrain (hb), cerebellum (cb), rhombomere 1 (r1). A. At e3.5, in a lateral view of a wholemount embryo, Raldh1 is located in the eye and presumptive locus coeruleus (LC) of ventral r1 (arrow). B. Dorsal view at e5. C. Transverse section (through level indicated by dashed line in B) identifies expression in the LC. D. Expression at e6 of Raldh1 in a transverse section through rostral rhombomere 1. E. Expression of tyrosine hydroxylase (TH) at e6 in a matched transverse section of rostral r1. F. Transverse section through r1 at e6 showing double in situ hybridisation for Raldh1 (blue) and Cath1 (red). G. Dorsal view of hindbrain at e6.5 showing bilateral expression within putative isthmo-optic territory (arrows). H. Transverse section through the mid/hindbrain (dashed line in G). I. Expression relative to the cerebellum (midbrain removed) in a lateral view at e7 (arrow). J. Expression in vestibuloacoustic territory at e7 (arrows).