Induction and Inhibition of Epithelial Differentiation by the Mixed Cell Aggregates of the Mesenchymes from the Chicken Embryonic Digestive Tract: (epithelial-mesenchymal interaction/mesenchymal cell aggregates/pepsinogen induction/gland formation/in vitro differentiation).

Epithelial-mesenchymal interaction plays an important role in the differentiation of digestive tract. However, the factors of these mesenchymes involved in induction of the epithelial differentiation of each organs are still unknown. In the present study, we made reconstituted mesenchymal cell aggregates by mixing proventricular mesenchymal cells with other mesenchymal cells, recombined the reconstituted mesenchyme with gizzard epithelium, and observed the differentiation of the gizzard epithelium in the explants with special attention to the appearance of embryonic chicken pepsinogen, one of the molecular marker of the proventricular epithelial cells, in the gizzard epithelium. The results showed that the proventricular mesenchymal cells induce gland formation and pepsinogen in the gizzard epithelium and that the esophageal and gizzard mesenchymal cells have the inhibitory influence on the differentiation of epithelia toward proventricular epithelium. The cells from small-intestinal, lung and dorsal dermal mesenchyme have no such effect. Based on the results obtained so far, a hypothesis was presented to explain the mechanism regulating the differentiation of the epithelium in the digestive tract in the chicken embryo.