title: Fine structure of-and some histochemical observations on-chondroid regions of benign mixed parotid tumours.
abstract: Seven cases of mixed parotid tumour were studied at the light-and of these, three-at the electron microscopical level. In the latter group, special attention was paid to the fine structure of the chondroid regions of the tumours. The chondroid regions showed a typical cartilage fine structure-of greater interest was the finding that this tissue was mixed type of both hyaline and elastic cartilage. This was evident with respect to both cell and extracellular matrix. Two cell types were found: (A) cells similar to cells of hyaline cartilage and (B) cells resembling cells shown to be involved in synthesis of elastic fibres (elastic tendon fibroblasts, elastic cartilage chondrocytes and arterial smooth muscle cells). As in normal calcifying cartilage the chondroid regions contain numerous membrane-delimited matrix vesicles. However, mineral deposits within the latter were rare, indicating either a suppressed tendency towards mineralization of a lower stage of tissue maturation at which the mineralization process has not yet started.
mesh_terms: D008949:Adenoma, Pleomorphic / Q000648:ultrastructure*; D002356:Cartilage / Q000648:ultrastructure; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D008297:Male; D008854:Microscopy, Electron; D010307:Parotid Neoplasms / Q000648:ultrastructure*