Product identification of ameloblastomas: an immunohistochemical study.

Twenty-nine solid, plexiform and follicular ameloblastomas and control human developing teeth at different stages of maturation were formalin-fixed, paraffin-embedded and sectioned for the study of laminin, fibronectin, and mannosyl, glucosyl, and galactosyl residues using the peroxidase antiperoxidase (PAP) and avidin-biotin peroxidase complex (ABC) staining methods, respectively. Monospecific antibodies to laminin and fibronectin and the affinity of the lectins for mannosyl, glucosyl, and galactosyl residues with RCA-I. Laminin is present during the stage of morphodifferentiation of normal tooth development within the basement membrane. Following cytodifferentiation and calcified matrix deposition, laminin is not detectable. Laminin is also found in the basement membrane of both follicular and plexiform ameloblastomas. In contrast, fibronectin is reactive only up to the stage of morphodifferentiation among the mesenchymal cells and at the epithelial-mesenchymal interface, and it becomes unreactive upon differentiation of odontoblasts and mesenchymal pulp tissue as well. Unlike laminin, fibronectin is unreactive in the basement membrane of plexiform follicular and ameloblastomas.