Double muscularis mucosae in Barrett's esophagus.

To clarify the histology and morphogenesis of the double muscularis mucosae in Barrett's esophagus, eight specimens resected from patients with Barrett's esophagus were compared histopathologically with 352 specimens resected from patients without Barrett's esophagus. A double muscularis mucosae was observed in seven (87.5%) of the eight cases with Barrett's esophagus, but in none of the 352 cases without Barrett's esophagus. The mucosa in the segment of Barrett's esophagus consisted of columnar epithelium, a superficial lamina propria, a superficial muscularis mucosae, a deep lamina propria, and a deep muscularis mucosae. The distal end of the superficial muscularis mucosae was connected to the deep muscularis mucosae at the esophagogastric junction, and its proximal end was located in fibrous tissue below the squamocolumnar junction of the mucosal epithelium or the distal edge of the erosive lesion. The deep muscularis mucosae in the portion with Barrett's esophagus was continuous with the original muscularis mucosae of the proximal esophagus and muscularis mucosae of the stomach. Barrett's esophagus is considered to be not merely a metaplastic lesion within the epithelium, but a newly developed lesion containing columnar epithelium, lamina propria, and a superficial muscularis mucosae on the lamina propria of the esophageal mucosa.     

Structural changes in the freeze-fractured sarcolemma of ischemic myocardium.

Ultrastructural alterations in the sarcolemma of ischemic myocardium were studied with the freeze-fracture technique. In normal myocardial sarcolemma, the P fracture face contained many intramembranous particles which were randomly distributed, while the E fracture face had few intramembranous particles; no structural abnormalities were seen within the lipid bilayer on either face. Myocardium ischemic for 45 minutes displayed no, or only slight, aggregation of intramembranous particles, but upon reperfusion for 5 to 20 minutes, the particles became significantly aggregated in the P face. Scattered nicks within the lipid bilayer were observed on both fracture faces. Intramembranous particles were similarly aggregated in myocardium ischemic for 2 hours; however, the number of nicks were greatly increased on the P and E fracture faces. These structural alterations, which were undetected in thin sections, are likely to be associated with altered function in the sarcolemma of ischemic myocardium.     

Acute jejunal ileus in intestinal lymphangiectasia

Summary A 26-year-old patient presented with epigastric pain of sudden onset and severe puffy swelling of both legs and forearms. An irregularly shaped nodular filling defect on selective jejunal films, severe hypoproteinemia, low IgG concentration, and lymphopenia were suggestive of primary intestinal lymphangiectasia with protein-losing enteropathy, and the patient was placed on a low-fat diet with medium-chain triglycerides. This initially improved his condition, but some weeks later he developed obstructive ileus of the small intestine. On laparotomy yellowish to whitish deposits were found to be present in some segments of the small intestine and a fist-sized mass 100 cm distal to the duodenojejunal flexure was resected without complications. Histologically, the submucosal lymphatics were dilated, and the jejunal wall showed extensive pseudocystic, intramural submucosal lymph edema with secondary bleeding and tight stenosis of the jejunal lumen. During the 14-month follow-up time after discharge the patient has been asymptomatic and working, on no treatment other than a low-fat diet with medium-chain triglycerides.     

Endotoxin-induced injury of the central, autonomic and enteric nervous systems and intestinal muscularis in Thoroughbred horses

To evaluate the effects of endotoxin on the morphology of the equine central, autonomic and enteric nervous system and intestinal muscularis, six Thoroughbred horses with experimentally induced endotoxaemia were examined. The lesions in the central nervous system consisted of perivascular oedema around arterioles, suggesting brain oedema, and ring haemorrhages around veins, similar to those in human patients with septic shock. In the cranial mesenteric ganglia, neuronal cell bodies became pink or red, with shrinkage of cytoplasm indicative of ischaemic changes; intramural and perivascular infiltration by erythrocytes and neutrophils occurred around arterioles in the epineurium (acute focal interstitial inflammation). In addition, transmission electron microscopy revealed oedema of the endoneurium and mesoaxon in the nerve fascicles running inside or outside the ganglia. Myenteric neurons showed shrinkage of the cytoplasm with multiple cytoplasmic vacuoles, suggesting ischaemic changes. Oedematous degeneration and coagulation necrosis of smooth muscle cells, with dissociation of the cells, were prominent in the tunica muscularis. It is suggested that arterionecrosis elicited by endotoxin and frequently observed in the autonomic and enteric nervous system and intestinal muscularis, was the result of vasoconstriction or vasospasm.     

Ultrastructure and biochemistry of ischemic damages of small intestinal epithelial cells.

Ischemia (one hour) and following reperfusion (up to one hour) of the small intestine induce biochemical changes which are indices for the formation and action of oxygen free radicals and which occur predominantly during the reperfusion period. But the villi and the epithelial cells show different patterns of damage, occurring both at the end of the ischemic period and during the reperfusion period. Although the quantitative morphological changes are increased during the reperfusion in comparison with the ischemic phase the quality of the pattern of structural damage is the same in both periods of the experiment. This pattern of the damage includes: 1. the neighbourhood of groups of villi with total ischemic-lytic dissolution of the villi, of villi with damage of the epithelial cells at the tip and at the lateral area and of normal villi; 2. the different degree of structural damage of neighbouring epithelial cells within one villus whose cells are either of regular structural or damaged at subcellular organelles including the plasma membrane or of those being necrotically destroyed and on the way of release into the luminal space; 3. a differentiation of the structural changes of the microvilli and other organelles within single and neighbouring epithelial cells. The biochemical findings on purine nucleotide metabolism and on the formation of oxygen free radicals as "mean values" of a homogenate from a large group of cells cannot reflect the morphological-ultrastructural changes of single villi or even single epithelial cells. The possible reasons for the mosaicism of the morphological changes during ischemia and reperfusion are discussed.     

Ultrastructural changes in the ischemic zone bordering experimental infarcts in rat left ventricles.

Ultrastructural changes in myocardial cells from the ischemic border of infarcts (produced in rat left ventricles by ligating the anterior coronary artery in vivo) were examined 1 to 24 hours after ligation. Twenty-four hours after ligation, irreversibly injured cells showed a selective spreading of Z-band material over the I band; disappearance of M bands, prominent N bands, and disassembly of A bands were also noteworthy. Sixty minutes after ligation the cells of the ischemic border were ultrastructurally normal except for paradoxically relaxed sarcomeres, indicative of an inability to contract in response to the calcium influx produced by osmium tetroxide; progressive vacuolization of this zone was evident after 4 to 12 hours. Paradoxical relaxation may be an ultrastructural correlate of acute ischemic "pump failure".     

Arrangement of the tunica muscularis in the ileal papilla of swine.

The arrangement of the bundles of muscular fibers in the ileal papilla was studied in 32 adult male crossbred swine by dissection of the muscular bundles in this region, after immersion in 50% nitric acid, and by observation under the stereomicroscope of material preserved in a 10% formaldehyde solution. In the ileal papilla, the cranial (ileocolic) contour of the tunica muscularis was formed by the circular strata of the ascending colon and the ileum, and the caudal (ileocecal) contour by the circular strata of the cecum and the ileum. The longitudinal stratum was located between the circular strata with predominance of muscular bundles originating in the terminal ileum. The tunica muscularis showed an increased thickness at the base of the eminence and at the free border, not reaching the apex. In the ileal papilla, the circular and longitudinal components characterize a "pylorus", the ileocecocolic or ileal pylorus as a transit regulation device for the flow of contents between the small and large intestine of swine.