Mucosubstance histochemistry of pleomorphic adenoma of parotid and submandibular salivary glands of man: light and electron microscopy.

Lumina and adluminal cells in human salivary gland pleomorphic adenomas were found to contain neutral, carboxylated, and occasionally sulphated glycoproteins. A variable component of luminal contents and secretory granules did not appear to contain glycoprotein and possibly consisted of protein. Glycosaminoglycans, which appeared to be hyaluronic acid and chondroitin sulphate, were demonstrated rarely in lumina, often between epithelial cells, and forming the matrix of myxoid tissue and, together with collagen, chondroid tissue. No differences were seen between tumours from parotid glands and those from submandibular glands. Glycoproteins demonstrated in the epithelium are similar to those of intercalary ducts of parotid and submandibular glands, and may represent a primitive form of salivary secretion. Glycosaminoglycans secreted intercellularly by epithelial cells cause their increasing separation to form myxoid or chondroid tissue. This stromalization extends to lumina to produce a loss of epithelium. Pleomorphic adenoma appears to be a manifest example of variable derepression of the genotype.

Ultrastructural observations on luminal structures of pleomorphic adenoma of parotid and submandibular salivary glands of man.

Luminal structures found in salivary pleomorphic adenomas consisted of lumina surrounded by epithelial cells that varied from being packed together to being widely separated except at the luminal margin. Communication between lumina and the surrounding stroma was occasionally seen. Secretory material and cellular debris were seen in lumina, invaginations of the luminal surfaces of periluminal cells, associated vesicles, and vacuoles. Secretory granules, lysosomes and lipofuscin were seen in periluminal cells. Secretory material and debris from necrotic periluminal cells appear to accumulate in lumina, and to be endocytosed and degraded lysosomally by periluminal cells. The finding of communications between lumina and the surrounding stroma suggests that the stromalization of the epithelium includes the luminal structures. The present investigation supports the hypothesis that many of the cellular features of the pleomorphic adenoma relate to the microenvironment.

Ultrastructural morphology of secretory granules in pleomorphic adenoma of human parotid and submandibular salivary glands.

Secretory granules were found in some of the cells lining the lumina of typical epithelial structures in pleomorphic adenomas. They were small, of varied electron density, and were mostly unipartite, sometimes bipartite and occasionally tripartite. They most closely resembled secretory granules of intercalary ductal cells of normal salivary glands.

Ultrastructural phosphatase histochemistry of submandibular and parotid salivary glands of man.

Thiamine pyrophosphatase was demonstrated in the Golgi complex and acid phosphatase in the GERL of acinar cells of submandibular and parotid glands and were previously demonstrated in cells of intercalary ducts. Thiamine pyrophosphatase was also demonstrated in the Golgi complex of cells of striated and excretory ducts and myoepithelial cells. Acid phosphatase was also demonstrated in lysosomes. Alkaline phosphatase was rarely demonstrated light microscopically at luminal surfaces of striated and excretory ducts and electron microscopically in luminal vesicles in cells of striated ducts. The demonstration of the phosphatases in Golgi complexes and GERLs indicates that investigations on these structures in experimental animals are relevant to human salivary glands and supports the opinion that ductal cells as well as acinar cells secrete organic material. The presence of alkaline phosphatase at luminal surfaces of striated and excretory ducts suggests that resorption as well as secretion may occur in them.

Mucin histochemistry of submandibular and parotid salivary glands of man: light and electron microscopy.

Light-microscopy showed parotid serous acinar cells to contain neutral mucin, serous and mucous acinar cells of submandibular gland and intercalary ductal cells of both glands to contain acid and neutral mucins, and cells of striated ducts and excretory ducts to contain neutral mucin. Mucins were demonstrated ultrastructurally in a portion of the components of secretory granules of acinar cells and intercalary ductal cells, and in secretory granules of striated and excretory ductal cells. The mucins were all stained by techniques that reveal 1,2-glycols. Secretory granules of submandibular mucous and serous acinar cells and intercalary ductal cells were stained variably by the low iron-diamine technique for acid mucin, and those of mucous acinar cells by the high iron-diamine technique for sulphomucins mucin and possibly consisted of protein. The results suggest that one type of cell may be able to produce a range of secretory products and to package them variously into secretory granules.

Ultrastructural morphology of secretory granules of submandibular and parotid salivary glands of man.

Morphological variation among secretory granules of the same type of cell was found in the acini, intercalary and striated ducts, and collecting-ducts, and was greatest in serous and intercalary-duct cells. Secretory granules of monopartite and bipartite structure were seen in all these cell types; tripartite forms were seen in serous and intercalary-duct cells. A possible explanation for the variation is that one type of cell may be able to produce a range of secretory products and package them variously into secretory granules, thus creating different appearances.

Ultrastructural cytochemistry of phosphatases in the ductal component of pleomorphic adenoma of human parotid and submandibular salivary glands.

Some ductal cells of pleomorphic adenomas showed evidence of secretory activity, with apical secretory granules, thiamine pyrophosphatase activity in the Golgi apparatus, and acid phosphatase activity in GERL-like structures and in immature secretory granules. Alkaline phosphatase activity was demonstrated rarely at the luminal plasma membrane and in intracellular vesicles, suggesting resorptive activity. ATPase reaction product was associated with contiguous surfaces of tumour cells, particularly of those cells adjacent to the basement membrane, these latter cells apparently differentiating in a different manner to the luminal cells. A comparison of luminal ductal cells of the tumours with normal salivary glands revealed most similarity with intercalary ductal cells.

Ultrastructural phosphatase cytochemistry of the intercalary ducts of the parotid and submandibular salivary glands of man.

Cells of the intercalary ducts showed concentrations of secretory granules adjacent to the luminal plasma membrane. Evidence of thiamine-pyrophosphatase activity was seen in the Golgi apparatus and of acid-phosphatase activity in GERL-like structure, lysosomes and immature secretory granules. Adenosine-triphosphatase reaction-product was present along surfaces of myoepithelial cells and to a lesser extent along contiguous surfaces of duct cells. The findings indicate secretory activity in the intercalary duct cells.