Pharyngeal segmentation is defective in fgf8-MO animals

Click on image to play QuickTime movie (4.2 MB).

fgf8MOfli.mov

Zebrafish embryo, from 12 hours (6-somite stage) to 38 hours, injected with fgf8-MO and expressing fli1-GFP.

The movie shows a lateral view of the pharyngeal region, anterior is to the left and dorsal is up. fli1-GFP expression initiates in crest cells as they arrive ventrally and the pharyngeal arches begin to form. However, whereas in wild-type animals the posterior branchial mass is subdivided into five segments by the pharyngeal pouches, in this fgf8-MO example one of the posterior pouches fails to fully form and only four posterior segments are made.