The purpose of this study is to elucidate the participation of Paneth cells in experimentally induced adenocarcinoma of the intestine. The rats were fed with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) dissolved in drinking water ad libitum at a concentration of 100 micrograms/ml for 28 weeks. They were sacrificed 12 weeks after the last MNNG administration. A number of tumor cells containing large eosinophilic granules in their supranuclear cytoplasm (Paneth cells) were observed in about 20% of the experimentally induced adenocarcinoma of the small intestine. The granules were stained positively with Lendrum, periodic acid-Schiff, Masson's trichrome, and Mallory's phosphotungstic acid hematoxylin. Ultrastructurally, the granules were round, osmiophilic, and relatively even in size. We compared the morphologic features of the Paneth cell-containing small intestinal adenocarcinomas (Group I) with those without Paneth cells (Group II). Group I was distinguished from Group II by its better differentiation, larger tumor size and lower incidence of calcification. Although Paneth cells are extremely rare in human gastrointestinal carcinomas, twenty percent of MNNG-induced intestinal carcinomas harbor Paneth cells. The neoplastic Paneth cells in experimental carcinomas may differentiate from uncommitted cells in the deeper portion of the crypt.
Adenocarcinoma/chemically induced/*ultrastructure ; Animals ; Cell Transformation, Neoplastic/chemically induced/ultrastructure ; Intestinal Neoplasms/chemically induced/*ultrastructure ; *Methylnitronitrosoguanidine ; Rats ; Rats, Inbred Strains

The present study was designed in order to investigate the lectin induced cytoagglutination properties of normal and transformed cells and surface alterations in the early stage of the transformed cells by characterizing the structural changes on the hepatoma surface membrane. Rat and rabbit erythrocytes and Sarcoma 180 ascites tumor cells were used for the lectin-induced cytoagglutination. Plotting % agglutination versus concanavalin A(Con A) concentration, sigmoid curves appeared in all cases. alpha-methyl-D-mannopyranoside(alphaMM) inhibited Con A induced cytoagglutination and the degrees of inhibition depended on the cell types and species. When rats were fed a diet containing 0.06% 3'-methyl-4dimethylaminoazobenzene(3'-Me DAB) for 12 weeks, almost all of the rats had solid liver tumors. Polyacrylamide gel electrophoresis of surface membrane proteins of these rat livers and of transplanted tumor cells showed three distinct protein bands, of which two were absent in normal rat livers. The molecular weights of these proteins were 73,000, 66,000, and 57,000 daltons. Antiserum against primary hepatocarcinoma surface proteins precipitated with three membrane proteins obtained from primary hepatocarcinoma cells as well as transplanted hepatocarcinoma cells, suggesting the presence of specific tumor antigens in these cells.
Animal ; Cell Membrane/pathology* ; Cell Transformation, Neoplastic/ultrastructure* ; Concanavalin A/diagnostic use ; Liver Neoplasms, Experimental/chemically induced ; Liver Neoplasms, Experimental/ultrastructure* ; Methyldimethylaminoazobenzene ; Rabbits ; Rats ; Surface Properties