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CONTENT - International Society of Zoological Sciences

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S23 ICZ2008 - Abstracts<br />

Organogenesis <strong>of</strong> digestive organs in vertebrates<br />

Sadao Yasugi<br />

Faculty <strong>of</strong> Pharmaceutical Science, Teikyo Heisei University, 2289,<br />

Uruido, Ichihara, Chiba 290-0193, Japan<br />

The embryonic digestive organs in the vertebrates consist <strong>of</strong><br />

endodermal epithelium and mesodermal mesenchyme. The former<br />

later fulfils functions such as production <strong>of</strong> digestive enzymes and<br />

absorption <strong>of</strong> nutrients, whereas the latter differentiates into<br />

connective tissue layers and smooth muscle layers. It has been<br />

well established that interactions between epithelium and<br />

mesenchyme are prerequisite for the normal development <strong>of</strong> the<br />

digestive organs. In general, the differentiation <strong>of</strong> the epithelium<br />

requires specific influence <strong>of</strong> the mesenchyme, and the<br />

differentiation <strong>of</strong> the mesenchyme and its nervous system is<br />

regulated by the epithelium.<br />

Recent studies carried out in my laboratory have revealed<br />

importance <strong>of</strong> some factors in the mesenchymal and epithelial<br />

tissues in the development <strong>of</strong> the chicken digestive organs,<br />

especially the stomach. For example, the determination <strong>of</strong> regional<br />

specificities <strong>of</strong> the epithelium in the primitive gut is <strong>of</strong>ten under the<br />

influence <strong>of</strong> the mesenchymal growth factors such as BMP, FGF<br />

and Wnt. On the other hand, the differentiation <strong>of</strong> the mesenchyme<br />

is controlled by sonic hedgehog expressed in the epithelium.<br />

The digestive organs possess essentially the same structures<br />

among the vertebrates. For example the stomach has glands cells<br />

<strong>of</strong> which produce and secrete digestive enzyme pepsin. The small<br />

intestine forms villus structures and epithelial cells produce<br />

dissacharidase and absorb nutrients. This means that factors<br />

acting in the development <strong>of</strong> the chicken digestive organs are also<br />

active in other vertebrates. In fact, above-mentioned growth actors<br />

and sonic hedgehog are known to be expressed in the developing<br />

stomach epithelium and mesenchyme <strong>of</strong> the mammals. Thus roles<br />

<strong>of</strong> these factors elucidated with he chicken embryo must also be<br />

important in other vertebrates.<br />

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