Electron microscopic studies of human pancreatic adenocarcinoma.

Tissue samples from 12 patients with pancreatic carcinoma were studied by light and electron microscopy. Ten were diagnosed as adenocarcinoma by light microscopy. However, three different electron microscopic findings were observed among these ten adenocarcinomas. One showed that the tumour cells had large nuclei with poorly developed intracellular organelles. Many mucinous granules, well developed cellular projections and intracellular microcysts were observed. In the second findings were different in that these cells had no granules. The intracellular organelles were developed poorly and abundant microvilli and cellular projections were observed. These observations suggest that the tumour cells may arise from pancreatic ductular cells. The third specimen showed a completely different appearance. There were pleomorphic nuclei with enlarged nucleoli and the cytoplasm contained swollen mitochondria, a well developed rough endoplasmic reticulum and varying numbers of zymogen-like granules. Occasionally, the zymogen-like granules were absent. These characteristics resemble the de-differentiation of acinar cells which has been repeated in experimental pancreatic carcinoma. These results suggest that careful examination of human pancreatic carcinoma may show more cells of acinar origin.