Ultrastructure of well-differentiated adenocarcinoma of the gallbladder.

The ultrastructure of four well-differentiated adenocarcinomas of the gallbladder was investigated by scanning and transmission electron microscopy and compared with the ultrastructure of nonneoplastic mucosa in the same specimens and of the mucosa of gallbladders with gallstones. The tumor cells seen by scanning electron microscopy had severe disorganization of the regular arrangement of columnar cells. They were bizarre in shape and size and were covered with less developed pleomorphic microvilli that were irregularly distributed. No such findings appeared in the control specimens. The tumor cells seen by transmission electron microscopy exhibited pleomorphic microvilli, well-developed cytoplasmic organelles, various mucus granules, abundant lysosomes, and nuclear changes. These findings suggest increased secretory and metabolic activity in the tumor cells. Gobletlike cells, Paneth-like cells, and endocrine cells were scattered in two of the carcinomas. These cells were also noted in the nonneoplastic mucosa of the carcinoma specimens but were rare in the mucosa when cholelithiasis was present.