[Distribution of the enterochromaffin ("EC") cells and those of the "APUD" series in the gastrointestinal tract of ruminants].

The research was carried out on the vorestomachs, abomasum and on the various tracts of gut of adult Cattle, Sheep and Goat, because Ruminants, not previously studied with respect to this problem, have, as is well known, particular morpho-functional characteristics of the digestive system. The results can be synthetized as follows: 1) either "EC" (5-HT-producing) or "APUD" cells (peptide hormones-producing) are not demonstrable in the vorestomachs. 2) "EC" cells are present in the various areas of abomasum (particularly numerous in the fundus glands) and in the different tracts of the gut (predominantly in the duodenum and in the rectum). 3) In the "APUD" cells of the abomasum gastrin-producing "G" cells are certainly demonstrable. They are present only in the pyloric glands, where they prevail in the middle third. Only in the cattle, cells which have all the histochemical characteristics of "G" cells, but are quite morphologically different, are also present in the same area. An interesting peculiarity seems to be the reduced number of "APUD" cells, compared with that of Monogastrics: it was impossible, in fact, to demonstrate some cells ("A", "A-like","X", "D", "D1", "ECL") which are described by other Authors in the stomach of various Mammals. 4) In the small intestine, endocrine cells, probably heterogenous are present, resulting more numerous in the duodenum. 5) In the coecum, colon and rectum, cells comparable to enteroglucagon-producing "EG" cells, are present; they are particularly numerous in the rectum, where cells similar to "H" cells are also present.