Fig. 7.

Schematic representation of morphological and gene expression changes in the exocrine pancreas during X. laevis metamorphosis. The adult frog pancreas has all of the types of ducts that have been described for adult vertebrates. Tadpoles lack the intercalated ducts. At the climax of metamorphosis, TH induces dedifferentiation of the exocrine pancreas to a progenitor state that has extinguished the mRNAs encoding terminally differentiated proteins (represented by amylase). PDX-1, Notch-1, and Hes-1 are up-regulated. Late in climax Ptf1a is reactivated followed by the differentiation of acinar and duct cells. Abbreviations: ac-acinar; ld-lobular duct, icd-intercalated duct. Figure is not drawn to scale.