THE ADENOMATOID ODONTOGENIC-TUMOR - ULTRASTRUCTURE OF TUMOR-CELLS ANDNON-CALCIFIED AMORPHOUS MASSES

The ultrastructure of tumour cells and tumour droplets (TD, non-calcif ied amorphous masses) was studied in three cases of AOT using freshly prepared tissue. The fine structure of the epithelial tumour cells (ce ll type I-III) corresponded to that of earlier descriptions. The extra cellular location of TD was clearly demonstrated. TD were of varying, sometimes bizarre, configuration. Some TD showed a homogeneous matrix; however, in addition most revealed electron-dense plaques. At high ma gnification, homogeneous types of TD showed only tubular elements; all others revealed granule-tubular structures. The tubular elements were arranged concentrically. The nature of the TD is discussed and compar ed to former interpretations. From the present ultrastructural finding s, it appears that the TD most probably represent some form of enamel matrix and as such may be considered a type of pre-enamel. Further stu dies are needed to elucidate the complex structure of the TD-material so characteristic of the AOT.