Ultrastructural studies of endocrine cell populations showing an argentaffin reaction and/or serotonin immunoreactivity in the rat antral mucosa

Ultrastructural classification of the endocrine cells of the large intestine of the calf. Cytochemical evidence of the presence of Viallis's pre-EC cells

GEP (Gastro-Entero-Pancreatic) endocrine cells were very numerous in the mucosal layer of the large intestine of the calf. Their frequence appeared to increase towards the distal portions of the gut. Endocrine cells were dispersed among epithelial cells lining intestinal glands and were frequently grouped together. Cellular shape was pyramidal or elongated; the cytoplasm was electron-lucent and contained highly characteristic secretory granules. Six different types of endocrine cells were identified on the basis of the ultrastructural aspect and cytochemical characteristics (silver-reactivity) of their secretory granules: EC, L, PP, A, D1 and D cells. EC and L cells were the most abundant in all localisations. They were especially numerous in the rectum. A subpopulation of EC cells was negative to Masson-Singh's reaction showing that they lack 5-HT. This observation enabled us to refer this latter cellular type to the "pre-EC" cells, described by Vialli as an earlier evolutive step of the EC cells population. Their presence in the calf gut might be linked to its possible "immaturity", due either to the age or to the alimentary diet.

A novel endocrine cell type in the guinea-pig gastric mucosa: cellular source of pro-enkephalin-derived peptides. A histochemical, immunohistochemical, and electron microscopical characterization

A novel endocrine cell type has been identified in the guinea-pig gastric mucosa which preferentially occurs in the oxyntic area. Cells of this type exhibit immunoreactivities for bovine adrenal medulla dodecapeptide (BAM-12P) and in many cases for Met-enkephalin and are thus presumed to contain a pro-enkephalin-like precursor protein. Systematic immunohistochemical investigations show that these cells do not contain immunoreactivities for various enteric hormones, neuropeptides and biogenic amines (serotonin, histamine). However, they do contain immunoreactivity for chromogranin A, an acidic glycoprotein which is common to the majority of entero-endocrine cells. Using silver impregnation techniques BAM-12P immunoreactive cells prove to be argyrophil, but fail to react argentaffin. On the electron microscopical level, these cells contain a well-developed endoplasmic reticulum and Golgi apparatus and numerous polymorphous secretion granules which measure about 290 nm in diameter. The secretion granules are ovoid or pear-shaped but largely plump compared to those of enterochromaffin cells. Light and electron microscopical findings indicate that BAM-12P immunoreactive cells constitute an endocrine cell population of the gastric epithelium in addition to the "established" endocrine cells hitherto known in this location.

The enterochromaffin cells in the mouse gastrointestinal tract after streptozotocin treatment

Effects of 5 weeks streptozotocin treatment on the mouse gastrointestinal tract were studied with special emphasis on enterochromaffin (EC) cells. In the streptozotocin-treated animals the frequency of EC cells was reduced in the antral area and in the small intestine, but increased in the colon. The length of the intestinal tract and the mucosal thickness were increased in these animals. Possible mechanisms underlying these abnormalities of the EC cell system are discussed.