Acinar and ductal cells of the normal pancreas express cytokeratin (CK) patterns which indicate a heterogeneity of ductal epithelia. On account of the CK of pancreatic adenocarcinoma, it would seem to be probable that tumor epithelia possess a considerable potential for squamous epithelium metaplasia. Comparative studies of CK expression by ductal carcinoma of the pancreas and carcinoma of bile ducts, stomach and large intestine as well in cases of chronic pancreatitis have demonstrated the usefulness of CK for differential diagnosis of these conditions. From the number of apomucins, mainly MUC1 is produced in the normal pancreas. This capacity is maintained in pancreas carcinoma and cell lines derived from it.