|Fig. 1. Endogenous expression of ski in Xenopus. Ski expression was first detectable in a ring around the blastopore at stage 10/11. At stage 20, strong expression was observed in bands in the forming head in the anterior (ant.) view There is also staining on the ventral mid- line immediately posterior to the cement gland at that stage. In a dorsal view, strong staining can be seen in the anterior spinal cord (black arrow) and the staining can be seen even fur- ther posterior at stage 22. Strong staining was also observed in the migrating anterior neural crest (red arrowheads). At tail bud stages (St. 30) low levels of expression are seen over much of the embryo including somites and higher expression was still viewed in discrete regions including the otic vesicle (yellow arrow).