RESUMEN
UNLABELLED: The great many hormones released by the endocrine cells of the glands and lining epithelium of gastric mucosa determine its significance for the processes in the gastrointestinal tract. One of these hormones, serotonin, plays an important role in the regulation of the motility, secretion and sensation in the gastrointestinal tract. The aim of the present study was to conduct immunohistochemical and electron microscopic studies of serotonin-producing EC cell of gastric mucosa. MATERIAL AND METHODS: Gastric mucosa biopsies were obtained and studied immunihistochemically for serotonin expression in the mucosa endocrine cells. Electron microscopic study was performed to specify the processes of synthesis, accumulation and release of secretory product by those cells. RESULTS: The immunohistochemical study revealed a considerable number of serotonin-containing EC cells scattered in the lining epithelium and between the glands in the corpus and pyloric region of the stomach. The electron microscopic study followed the stages of formation of the secretory granules from the initial accumulation of granular substance, its membrane packing and formation of mature granules to their disintegration in the secretory process. CONCLUSIONS: Serotonin as a neurotransmitter and gastrointestinal hormone appears to be a key to understanding a number of symptoms of gastrointestinal disorders like nausea, vomiting, pain, diarrhea and constipation. A detailed study of serotonin functions in the gastrointestinal tract realised through different types of receptors, and of the development of specific antagonists and agonists to these receptors would open up new opportunities for a more efficient treatment of gastrointestinal disorders.
Asunto(s)
Células Enterocromafines/metabolismo , Células Enterocromafines/ultraestructura , Mucosa Gástrica/metabolismo , Mucosa Gástrica/ultraestructura , Serotonina/biosíntesis , Anciano , Femenino , Humanos , Inmunohistoquímica , Microscopía Electrónica de Transmisión , Persona de Mediana Edad , Vesículas Secretoras/metabolismo , Vesículas Secretoras/ultraestructuraRESUMEN
UNLABELLED: The gastrointestinal tract in the early prenatal development is an endoblastic mesenchyme-lined tube. The endoblast differentiates and gives origin to all epithelial structures (covering epithelium, glands). The mesenchyme develops into connective tissue, blood vessels, the smooth muscle cells of lamina muscularis mucosae and muscular tunic. Neuroectoblast cells participate in these processes--individual cells with future endocrine function, nerve cells and fibers that form nerve plexuses and vegetative ganglia. AIM OF THE PRESENT STUDY: To trace the changes in the small intestine development during the prenatal period in rat embryos and fetuses, and during the postnatal period in newborn rats. We specifically studied the beta-actin expression in the cytoskeletal structures of the covering epithelium and in the contractile elements of the differentiating smooth muscle cells. The presence and localization of the enteroendocrine EC cell was studied using the immunohistochemical expression of serotonin in them. MATERIAL AND METHODS: Material from rat embryos and fetuses aged 8-11, 12-15, 16-20 days of gestation and small intestine fragments from newborn rats was studied using routine hematoxylin-eosin staining, enzymohistochemically for succinate dehydrogenase and immunohistochemically for beta-actin and serotonin. RESULTS: In the early embryogenesis (8-11 day of gestation), the primitive gut of rat embryos is an endoblastic tube of 2-3 layers of cuboidal cells covered with a thin layer of mesenchyme. In the subsequent stages of embryonic and fetal development the processes of differentiation run at different rates in the different tissues. The maturation process in the small intestine wall of one-day-old newborn rats is incomplete. The mucosa presents with shallow crypts and loosely set villi. Differentiated resorptive and enteroendocrine EC cells are found in the lining epithelium. CONCLUSION: The changes we found in the beta-actin expression in the contractile elements of the differentiating smooth muscle cells and the cytoskeletal structures of the lining epithelium probably reflect the induction interference between the derivatives of the mesenchyme and endoblast.