[Cytokeratin expression in fetal lung--immunohistochemical studies]

This paper is to give information about the pattern of expression of cytokeratin in bronchial mucosa, alveolar epithelium, lung stroma and pleura during the prenatal development of the lung. Our immunohistochemical investigations occurred in the lung of a 6 week old embryo and in 21 lungs of intrauterine died fetuses from the 12th to the 36th week of gestation according to the modified avidin-biotin-method. Findings of investigations will be compared with expression patterns in tumors and normal lungs of adults. In summary the investigations showed the following results: 1. Immunohistochemically in fetal lungs proteins are demonstrable that are used in the pathology of adults as markers for the histogenetic differentiation of various cell forms. 2. An expression of cytokeratins we could constantly prove in epithelial cells of fetal lungs after the 6th week of gestation. 3. Cytokeratins are mostly found at the cell membranes. 4. With increasing differentiation in direction to alveolar epithelium changes the composition of cytokeratin in the cells. 5. Cells of the pleura mesothelium are expressing cytokeratins in a pattern similar to that of bronchiolar epithelium. All in all the pattern of antigenic expression in fetal lungs considerably assimilates to that in adult lungs during the fetal lung development.