InhaltsangabeAcknowledgements.-Introduction and questions.-Materials and methods.-Light microscopy.-Lectin staining.-Immunohistochemistry.-Scanning electron microscopy.-Transmission electron microscopy.-Corrosion vacular casts.-Reverse transcription polymerase chain reaction and Western blot.-Animal investigations/experiments.-Results.-The epithelium and the underlying lamina propria of the nasolacrimal ducts.-The membranous part of the nasolacrimal ducts.-Absorption experiments in the nasolacrimal ducts.-Pathologic findings in dacryostenosis.-Discussion.-Mechanisms of immune defense in the nasolacrimal ducts.-Mechanisms regulating tear flow through the nasolacrimal ducts.-Absorption of tear fluid components.-Insights into the pathophysiology of primary acquired dacryostenosis.-Considerations on the relationship between dry eye and the nasolacrimal ducts.-Outlook.-Summary.-References.-Subject index