Cytokeratin Expression in the Stomach Epithelia of the Chicken Embryo is Regulated by Epithelial-Mesenchymal Interactions

Regulatory mechanisms of cytokeratin expression in the stomach (the proventriculus and the gizzard) epithelia of chicken embryos were examined by epithelial-mesenchymal recombination experiments. In the proventriculus, antigens detected by monoclonal antibodies (PKK1 and AE3) against cytokeratins invariably decreased in gland cells which synthesize pepsinogen, while luminal and duct epithelial cells were positive to these antibodies. When recombined and cultured with the proventricular mesenchyme, the esophageal, proventricular and gizzard epithelia formed proventriculus-type, pepsinogen-expressing glands and the expression patterns of PKK1 and AE3 antigens were identical to that in the normal proventriculus. Under the same experimental conditions, the small-intestinal and allantoic epithelia also formed complex glands but did not express pepsinogen, and PKK1 and AE3 antigens were actively expressed throughout the epithelia. These results indicate that the proventricular mesenchyme can regulate c...