Keiichi Katsumoto, Kimiko Fukuda, Wataru Kimura, Kenji Shimamura, Sadao Yasugi and Shoen Kume, Origin of pancreatic precursors in the chick embryo and the mechanism of endoderm regionalization. Mechanisms of Development doi:10.1016/j.mod.2009.03.006
To study the developmental origin of the pancreas we used DiI crystals to mark regions of the early chick endoderm: this allowed correlations to be established between specific endoderm regions and the positions of their descendants. Endodermal precursor cells for the stomach, pancreas and intestine were found to segregate immediately after the completion of gastrulation. Transplantation experiments showed that regional specific endodermal fates are determined sequentially in the order of stomach, intestine, and pancreas. Non-pancreatic endoderm transplanted to the stomach region generated ectopic pancreas expressing both insulin and glucagon. These results imply that a pancreas-inducing signal is emitted from somitic mesoderm underlying the pre-pancreatic region, and this extends rostrally beyond the stomach endoderm region at the early somite stage. Transplantation experiments revealed that the endoderm responding to these pancreatic-inducing signals lies within the pre-pancreatic region and extends caudally beyond the region of the intestinal endoderm. The results indicate that pancreatic fate is determined in the overlapping region between these two.
Figure: Mechanisms of the pancreas development in the early endoderm.
The endoderm competent to respond to the pancreas inducing signals lies within the pre-pancreas endoderm and expands caudally beyond the pre-intestine endoderm (pastel pink). Mesoderm which has pancreas inducing signals lies within the pre-pancreas region and expands rostrally beyond the pre-stomach region (beige). The pancreas region is then generated in the overlapping region (shaded pink) of the two regions (pastel pink and beige). Blue; stomach region, Green; intestine region.
