Epithelial cell differentiation is accompanied by biochemical and immunological changes of cytoplasmic components. Antibodies against filamentous and nonfilamentous substances of epithelial cells are helpful for the visualization of the gradual maturation processes in different epithelia. The present study is concerned with differentiation characteristics of the normal cervical mucosa and, in particular, the squamocolumnar junction. Antibodies against tissue polypeptide antigen (TPA), large keratins (67K), and all keratin fractions were applied in this investigation. Antibody binding was revealed by indirect immunofluorescence. TPA was found to be characteristic for basal layer cells and undifferentiated reserve cells of the transformation zone. In contrast, 67K represent an indication of squamous differentiation and were only found in suprabasal cells of the ectocervical epithelium and in keratinizing cells of the transformation zone. Antibodies against all keratin fractions were seen to label all epithelial cells. The immunomorphological definition of epithelial compartments of the normal cervical mucosa supports earlier concepts of the physiological processes at the squamocolumnar junction and represents an interesting tool for studies of cervical neoplasias of various differentiations.
