Disposition of muscularis propria and nerve elements in the lip of the ileocaecal valve.

The presence of a valve and the concept of a functional sphincter at the ileocaecal junction have been debated in the literature. Twenty four specimens of ileocaecal organ complex including 10cm of ileum and colon were obtained from cadavers from the Departments of Anatomy and Pathology, PGIMER, Chandigarh. 5 micron thick longitudinal sections from the upper lip of the ileocaecal valve were stained with Hematoxylin and Eosin and Silver stain. Sections of the ileum and colon from 5 ileocaecal organ complexes were also prepared and similarly stained. All the sections were viewed under the light microscope. The muscle bundles constituting the muscularis propria in the ileocaecal valve were arranged in two rows and were tapering in size from the base to the apex. The disposition of the muscle fibres was not uniform in all the specimens. The muscle fibers could be traced up to the upper, middle and lower third of the valve in 8 (33.3%), 14 (58.3%) and 2 (8.3%) specimens respectively. Silver stain of these sections revealed large numbers of nerve elements distributed within the submucosa and muscularis propria. The density of nerve elements in the ileocaecal valve was similar in all the sections irrespective of the extent of the muscularis propria and was comparable to the density of nerve elements in the muscularis propria and submucosa of the ileum and colon. The present study shows that the ileocaecal valve has a well developed muscularis mucosa and a proportionate component of the nerve elements.

Serosal patch of the gastroesophageal junction an experimental study in dogs

Thirty two dogs were operated on in order to evaluate the mucosal regeneration of the serosal patch at the gastroesophageal junction. The operation began with a cardiotomy involving one centimeter of the esophagus and two centimeters of the stomach, originating an elliptical serosal surface three centimeters long and one centimeter large, turned to the digestive lumen. The animals were divided into four groups of eight dogs each and named: 1,2,3 and 4; they were sacrified after one, two, four and eight weeks respectively. The results were evaluated by post-operative clinical aspects, macro and microscopic analysis. Post-operative morbidity was low, without signs of digestive tract obstruction. Macroscopically, the patch area at the first week became an ulcerated lesion, with a necrotic bottom; at the second and fourth weeks there was a progressive reduction of the ulcer, from its boundaries to the center, until the complete healing at the eighth week. Microscopically, the serous membrane disappeared early and it was replaced by inflamatory cells and severe neovascular formation, which fitted as a bed to the epithelial proliferation. The neo-epithelization occurred from the periphery to the center lesion. At the esophagus this process was completed within two weeks, with multiple layers of cells, at the stomach, within four weeks, with an unicellular epithelium. The corium, showing an inflamatory reaction at the first week, with fibrinoid necrosis and polimorphonuclear cells, changed to a fibroblastic proliferation with mononuclear cells at the second and fourth weeks and, finally, to fibrosis at the eighth week. In the animals sacrified lately there was regeneration of the snooth muscle layer of the esophagus. At electronic microscopy, the neo-epithelium of the esophagus had all the layer which constitute the normal esophageal epithelium.

Rat colon epithelium response to hypoxia is modified by intrinsic innervation blockade

Background/Aim: Short-circuit current (Isc) and transepithelial potential difference (PD) of rat distal colon decrease during acute hypoxia and overshoot on reoxygenation. It is not known whether tonic intrinsic nervous activity may influence these responses. Methods: Preparations lacking the submucosal plexus (isolet mucosa) and preparations retaining it (mucosa-submucosa) were mounted in Ussing chambers at 37 degrees Celsius and gassed with 95 percent O2 -5 percent CO2; Isc and PD were monitored. A 5-min hypoxia with 95 percent N2-5 percent CO2 was followed by reoxygenation. The procedure was repeated in the presence of the nervous blocking agent, tetrodotoxin (10(-6)M) in the serosal side of the chamber. Results: In the isolated mucosa (n=10) hypoxia reduced Isc by -55 + 5 percent and PD by -54 + 6 percent below baseline; reoxygenatory overschoots were, respectively, + 60 + 17 percent and + 16 percent. Tetrodotoxin slightly and transiently reduced baseline Isc (-16 + 2 percent) and PD (-14 + 3 percent), with a small resistivity increase. It did not significatively modify the responses to responses to either hypoxia or reoxygenation. In mucosa-submucosa preparations (n=9) hypoxia reduced Isc (-54 + 8 percent) and PD (-61 + 4 percent). On reoxygenation Isc and PD were increased, respectively, +30 + 5 percent and +19 + 6 percent over baseline. Tetrodotoxin reduced baseline Isc (-59,6 + 5 percent) and PD (61,3 + 6 percent). It enhanced hypoxic Isc and PD decreases (-80 + 5 percent), but not the reoxygenatory overschoots. Conclusions: 1) Tetrodotoxin affects baseline Isc and PD more intensely in submucosal plexus innervated preparations than in the isolated mucosa. 2) The epithelial electrical response to acute hypoxia appears to be modulated by tonic neural activity.

Fisiología del transplante intestinal: progresos recientes; parte 1 / Physiology of intestinal transport: recent advances (I)

La fisiología del transporte intestinal de electrolitos es de suma importancia para la compresión de las enfermedades diarréicas. El sistema nervioso entérico desempeña un papel relevante en la regulación neural del transporte intestinal de iones, y varias sustancias paracrinas, endócrinas y neurohumorales, así como el sistema renina-angiotensina, el balance sistémico ácido-básico, y los segundo mensageros, también parecen estar relacionados. Los propósitos de esta revisión son considerar los hallazgos recientes en la fisiologia del transporte intestinal de electrolitos