Fig. 3. Slug overexpression in the chick hindbrain increases the production of neural crest cells from the dorsal neural tube. (A) Embryo showing ectopic Slug expression at the right side of the hindbrain all along its dorsoventral axis. This section was taken from the embryo shown in Fig. 2B at the level indicated by the dotted line. Observe that Slug-expressing cells do not migrate from intermediate or ventral levels of the neural tube. A higher number of migratory cells can be observed in the electroporated side, some of which do not express HNK-1. This can be better observed in the magnification shown in B, where the existence of different migratory populations is readily apparent. Black arrowheads indicate Slug-positive/HNK-1-negative cells; white arrowheads exemplify the double-labelled population and black arrows indicate examples of Slug-negative/HNK-1-positive cells (see text). These populations are also detected both in the control side of the electroporated embryos (A) and in control embryos such as that shown in C-E, hybridised with Slug and subsequently stained with HNK-1. A section at the level of r6 is shown in E.
