Molecular analysis of the determination of developmental fate in the small intestinal epithelium in the chicken embryo.

Determination of the developmental fate in the small intestinal epithelium of the chicken embryo has not been fully analyzed up to the present. This study was carried out to analyze the determination time of the developmental fate of the small intestinal epithelium under the influence of other mesenchymes. The small intestinal epithelium reassociated and cultivated with the proventricular or gizzard mesenchyme or the dermis expressed chicken intestinal fatty acid binding protein, sucrase and CdxA as occurs during the normal development of the small intestinal epithelium. The presumptive intestinal endoderm taken from an earlier stage embryo and associated and cultivated with the proventricular or gizzard mesenchyme, showed gene expression patterns which were the same as those found in normal development. However, when the dermis was associated, the epithelium expressed sonic hedgehog, but never expressed intestinal epithelial- or stomach epithelial-markers. These results indicate that the determination of the developmental fate in the small intestinal epithelium and acquisition of autodifferentiation potency occur at the early stage of the gut development. Moreover the presumptive intestinal endoderm needs the supportive influence of the gut mesenchyme in order to differentiate fully into the intestinal epithelium.