Ultrastructural features of the epithelial-mesenchymal interface in an ameloblastic fibro-odontoma.
The ultrastructural features of the epithelial-mesenchymal interface in a case of an ameloblastic fibro-odontoma was studied with special reference to possible signs of "inductive" processes. In most parts of the tumor, the odontogenic epithelium was separated from the connective tissue by a thick rim of a finely filamentous meshwork in which a basal lamina was occasionally observed. Mesenchymal cells were seen to touch the filamentous meshwork but no membrane bound matrix vesicles were recorded. Small areas of dentin-like tissue were found in the juxtaepithelial connective tissue while enamel-like areas and spherical calcified masses were encountered in epithelial islands. The organic matrix in relation to the enamel-like tissue consisted of either tubular fibers or a fine-granular material. It was assumed that the tubular matrix component directed the formation of long enamel-like crystals, and that the fine-granular matrix was degraded tubular fibers in which spherical calcified masses might arise. Spherical calcified masses could be found in separate follicles also where they were related to a fine-fibrillar matrix or collagenous material. The cell layers forming the wall of the islands had a great resemblance to those of an enamel organ, but the findings of dentin-free, enamel-like areas are not compatible with the inductive theory of normal odontogenesis.
D002118:Calcium; D002648:Child; D003094:Collagen; D003238:Connective Tissue / Q000648:ultrastructure; D003461:Crystallography; D003743:Dental Enamel / Q000648:ultrastructure; D004847:Epithelial Cells; D004848:Epithelium / Q000648:ultrastructure; D005260:Female; D006801:Humans; D008339:Mandibular Neoplasms / Q000648:ultrastructure; D008648:Mesoderm / Q000648:ultrastructure; D009808:Odontogenic Tumors / Q000648:ultrastructure*
D003094:Collagen; D002118:Calcium