267
Digestive and Respiratory System
FIGURE 18.5 Combinatorial signals regulating Xenopus organ fate induction and expression of selected lineage-promoting transcription
factors. (A) Schematic of stage NF35 Xenopus gut tube (yellow). Pink shading represents splanchnic mesoderm, the source of most of the
indicated signaling molecules (exception of HH, which is produced by the endoderm). Organ primordia indicated in green along the endoderm gut tube. (B) In situ hybridization of the indicated genes in stage NF35 X. laevis embryos. Expression domains are as follows: foxe1,
pharyngeal endoderm; sox2, pharyngeal, foregut, stomach endoderm; nkx2–1, thyroid, lung/trachea endoderm; pdx1, dorsal and ventral
pancreatic, stomach endoderm; ptf1a, dorsal and ventral pancreatic endoderm; onecut1, dorsal and ventral pancreatic, stomach, liver, gall
bladder endoderm; shh, pharyngeal, foregut, stomach, gall bladder endoderm; dhh, foregut, midgut, hindgut endoderm; osr1, foregut, midgut, hindgut endoderm; cdx2, midgut and hindgut endoderm; gata4, heart, foregut, midgut endoderm; satb2, hindgut endoderm.
Digestive and Respiratory System
FIGURE 18.5 Combinatorial signals regulating Xenopus organ fate induction and expression of selected lineage-promoting transcription
factors. (A) Schematic of stage NF35 Xenopus gut tube (yellow). Pink shading represents splanchnic mesoderm, the source of most of the
indicated signaling molecules (exception of HH, which is produced by the endoderm). Organ primordia indicated in green along the endoderm gut tube. (B) In situ hybridization of the indicated genes in stage NF35 X. laevis embryos. Expression domains are as follows: foxe1,
pharyngeal endoderm; sox2, pharyngeal, foregut, stomach endoderm; nkx2–1, thyroid, lung/trachea endoderm; pdx1, dorsal and ventral
pancreatic, stomach endoderm; ptf1a, dorsal and ventral pancreatic endoderm; onecut1, dorsal and ventral pancreatic, stomach, liver, gall
bladder endoderm; shh, pharyngeal, foregut, stomach, gall bladder endoderm; dhh, foregut, midgut, hindgut endoderm; osr1, foregut, midgut, hindgut endoderm; cdx2, midgut and hindgut endoderm; gata4, heart, foregut, midgut endoderm; satb2, hindgut endoderm.