Fig. 2. Expression pattern of Bmp5 (A-E) and Bmp7 (F) in r1 during early stages of chick development. (A) Whole-mount in situ hybridisation for Bmp5 at stage 10 demonstrates expression in the rostral hindbrain, including r1 (white arrow, Bmp5 expression; black arrow, midbrain-hindbrain-constriction). (B) Simultaneous detection of Bmp5 and Fgf8 at stage 11 by whole-mount in situ hybridisation demonstrates an overlap (arrowhead) of Bmp5 (white arrow) and Fgf8 (black arrow) expression in r1. (C,D) Transcripts of Bmp5 (arrows) are found at stage 11 throughout the dorsal aspect of r1, at both rostral (C) and caudal (D) regions. Note that there also seems to be expression in the epidermal ectoderm (D). At stage 14/15, transcripts of Bmp5 (arrow) are restricted to the roof plate and dorsal edges of the neural tube (E), while Bmp7 expression (arrow) is restricted to the overlying epidermal ectoderm (F). Whole-mount in situ hybridisation was used for the detection of BMP5 in C,D, resulting in the collapse of the ventricle when compared with hybridisation of sections (Fig. 4C).