Fig. 4. Toddler functions as a motogen.
Ubiquitous or localized expression of Toddler promotes animal pole–directed endodermal cell migration in toddler mutant embryos. Toddler was expressed either vegetally from the yolk syncytial layer (YSL) (injection of toddler mRNA into the YSL) or animally from a toddler-overexpressing (OE) clone of cells transplanted into the animal pole. Dextran red injections into the YSL and transplantation of uninjected toddler mutant cells served as controls. Different treatments are illustrated on top; toddler expression domains are highlighted in cyan. All sox17 in situ hybridization images are lateral views of embryos at 70% epiboly (dorsal to the right).