<qa>  How many patients operated on for benign diseases served as control?18 out of 32 cases were eligible for analysis. Four patients operated on for benign diseases served as control and 14 patients with operable local gastric adenocarcinoma 4 mucosasubmucosamuscular y 10 serosa lesions were studied. At the beginning of surgery, a 2 x 2 cm. sample from macroscopically normal visceral peritoneum at mesenterium root was carefully obtained, washed with saline and fixed in glutaraldehyde solution. Besides a sample of peritoneal washing fluid was studied to exclude patients with free cancer cells. Peritoneal tissue was fixed during 24 hours and then all samples were evaluated by electronic microscope. 