Morphological and histochemical studies on APUD-cells in the lung epithelium are reviewed. Common features of these cells are their capacity to produce and store amine, their argyrophilia and their characteristic cytoplasmic secretory granules. Based on the fine structural morphology of the secretory granules three types of cells were observed in human foetal lung. In the human adult lung, endocrine cells were few in number and widely scattered. Contact between endocrine cells and nerves was never seen. One 'function' of endocrine cells in the human adult lung may be to act as precursor cells for carcinoid tumours and small cell anaplastic carcinomas (the APUDomas of the lung).

APUD Cells↗

PubMedDate not supplied

[Histopathological studies of the acute and chronic toxic effects of 2 N-nitroso compounds on the blue mussel (Mytilus edulis)].

The acute and chronic effects of two N-Nitroso compounds (N-Nitrosodimethylamine) (DMN) and N-Methyl-N-Nitro-N-Nitrosoguanidine (MNNG) were studied by light microscopy after injection of the chemicals into the foot of the mussel, Mytilus edulis. Acute toxic effects: DMN produced dose-dependent (0.1 to 0.8 mg DMN/mussel) tissue alterations characterized by extensive inflammatory reactions in the Leydig cell tissue of the digestive gland, and necrosis in the germinal epithelium lining the genital ducts. MNNG produced dose-dependent (0.063 to 0.5 mg MNNG/mussel) tissue alterations characterized by extensive necrosis in the epithelial lining of the tubules of the digestive gland. Chronic toxic effects: 0.2 mg DMN/mussel given once a week for 8 weeks, and examined over a period of 30 weeks, revealed tissue alterations characterized by extensive collagenous scar tissue formation in between the tubules of the digestive gland, presence of numerous granulocytomas, and necrosis of the germinal epithelium of the genital ducts. 0.125 mg MNNG/mussel given once a week for 4 weeks, and examined over a period of 7 months, produced tissue alterations mainly characterized by encapsulation or replacement of damaged digestive tubules by collagenous scar tissue.

Animals↗