Light and scanning electron microscope examination of the digestive tract in peppered moray eel, Gymnothorax pictus (Elopomorpha).

The morphology of the digestive tract of the peppered moray eel, Gymnothorax pictus (G. pictus) (Elopomorpha: Anguilliformes) was examined using both light and scanning electron microscopy. The digestive tract is composed of the esophagus, the stomach, and the intestines; pyloric caeca were absent. The stomach was divided into a cardiac region that was continuous with the esophagus, a body which terminated in a long blind sac, and a pyloric region that was continuous with the intestine. The short intestine possessed several partitions that were created by the mucosal folds within the posterior region. The terminal region of the stomach was characterized by the thick longitudinal muscularis and subserosa, and the gastric glands and microvilli were absent. Ciliary tufts of ciliated cells were observed on the surface of the partition-like mucosal folds within the intestinal wall. Acidic mucus was secreted throughout the digestive tract. It was suggested that the terminal region of the stomach is specialized for storage of large food items. In addition, it is possible that the partition-like mucosal folds within the intestine perform a function similar to that of the spiral valve and, and along with ciliated cells, facilitated digestion and absorption. The acidic mucus likely maintained surface epithelium pH and protease activity. Within a phylogenetic context, the absence of a pyloric caeca in G. pictus while possessing an intestine implies that this species is affiliated to groups that had branched off earlier than basal teleosts. Inc.

Three-dimensional organization of lymphatics in the dog stomach: a scanning electron microscopic study of corrosion casts.

The three-dimensional organization of the lymphatics in the dog stomach was studied by scanning electron microscopy of corrosion casts, which were made by direct parenchymal injection of low-viscosity Mercox-resin into the mucosa and the muscular layers. Although the organization of lymphatics in the stomach has been studied by a variety of methods, the origin of the lymphatics and their connection in each layer has not been clearly defined. In this study, using dog stomach because of its structural similarity to the human stomach, we defined the lymphatic structure in all gastric layers, with lymphatics absent in the upper two-thirds of the lamina propria mucosae. They were first encountered at the deepest level of the lamina propria, immediately above the lamina muscularis mucosae. These lymphatics were composed of single-layered irregular meshes. Slender lymphatics arising from this network passed through the lamina muscular is mucosae and drained into the lymphatic plexus, which was composed of thicker lymphatics at the uppermost layer of the submucosa. Lymphatic valves were frequently seen in this plexus. From this plexus, slender connecting lymphatics with valves extended straight downward without lateral communications and drained into the lymphatic plexus at the deepest layer of the submucosa. This latter plexus, composed of large-caliber lymphatics, issued flattened lymphatics which formed a three-dimensional network in the muscular layer. The subserosal lymphatics were composed of thick lymphatics with tortuous courses and drained into the efferent lymphatics.

Gastric lipase and pepsinogen during the ontogenesis of rabbit gastric glands.

In rabbit stomach, gastric lipase activity level was found to increase from birth to 30 days old (weaning), and then decreased. In contrast, pepsin activity only appeared between 30 to 45 days old, and increased till to the adult level. It was observed that maturation of gastric glands in cardial mucosa was a downward elongation process from the mitotic cell pool. These mitotic cells were always found in the neck of the gastric glands, corresponding to the bottom of the gland at 6 days old and to the mid-zone of the gland in adult. Location of rabbit gastric lipase (RGL) cells in cardial glands varied with age and was found along the pit of the gastric glands at 6 days old. The extent of this cellular location decreased with age, whereas a second RGL cell zone appeared below the mitotic cell area at 18 and 30 days old. At 45 days old, the pepsinogen cells appeared in the bottom of the gland, and consequently the RGL cells were located in the mid-zone of the gastric glands, between mitotic cells (neck of the gland) and pepsinogen cells (lower part of the gland). Ultrastructural study of cardial gastric glands revealed different morphologies of the secretion granules in the cells along the gastric glands. In 6-day-old rabbits, secretory granules were found uniformly electron dense in the bottom of the glands and were RGL-labeled by the immunogold technique. In the medium part of the glands, granules appeared biphasic, with a clear and a dense part, and RGL labeling was confined to the electron-dense part.(ABSTRACT TRUNCATED AT 250 WORDS)

[Electron microscopic verification of adenocarcinoma of the cardioesophageal area]. / Ob élektronno-mikroskopicheskoi verifikatsii adenokartsinomy kardioézofageal'noi zony.

Normal gastric and esophageal cardiac glands as well as proper esophageal glands were studied electron-microscopically. Cardiac gastric and esophageal glands were found to differ by chief cells available in the gastric glands and greater amounts of endocrine cells registered in the esophageal glands. The evidence can provide grounds for electron microscopic verification of cardioesophageal adenocarcinoma permitting the pathologist to rest upon the presence of cells resembling those of proper gastric glands and epigastric fossa. In addition, it can promote specification of the morphologic type of adenogenic esophageal cancer comprising squamous epithelial component and secretory granules typical of proper esophageal glands.

Ultrastructure of the peritrophic membrane-secreting cells in the cardia of the blowfly, Lucilia cuprina.

Scanning and transmission electron microscopy are used to reveal the internal anatomy and ultrastructure of the cardia which is the source of the triple layered peritrophic membrane in the blowfly Lucilia cuprina. Within the cardia, rings of secretory cells (formation zones) and non-secretory tissue (valvula cardiaca) interlock to secrete and mould the layers of membrane. Formation zone cells have abundant rough endoplasmic reticulum, Golgi and secretory vesicles. A portion of midgut just posterior to the formation zone is covered by close-packed microvilli connected by septate-like junctions. The cuticle-lined valvula cardiaca is rich in smooth endoplasmic reticulum, glycogen and microtubules. The oesophageal cuticle is unusual in containing tubular structures. The ultrastructural features of the separate components of the cardia are discussed in terms of their secretory and non-secretory roles; modified midgut cells secrete chitin and protein whereas modified foregut tissue (valvula cardiaca) appears to be adapted to provide structural integrity (extensive junctions, microtubules), movement (muscles, possibly microtubules), a store of energy (glycogen deposits) and possibly a lipidic secretion (from smooth endoplasmic reticulum) to lubricate the passage of the membranes.

Sensory vagal innervation of the rat esophagus and cardia: a light and electron microscopic anterograde tracing study.

Wheat germ agglutinin-horseradish peroxidase conjugate (WGA-HRP) was injected into nodose ganglia of rats. In the esophagus and cardia, dense networks of anterogradely labeled fibers and beaded terminal-like arborisations were observed around myenteric ganglia after combined histochemistry for HRP and acetylcholinesterase. The muscularis externa and interna proper were free of label except for a few traversing fibers. Submucosal and mucosal labeling was rather sparse except for the most oral part of the esophagus, where a dense mucosal innervation was found. Control experiments including WGA-HRP injections into the cervical vagus nerve, nodose ganglion injections after supranodose vagotomy, and anterograde [3H]leucine tracing from the nodose ganglion indicated that all labeled fibers in the esophagus and cardia originated from sensory neurons in the nodose ganglion. Electron microscopy revealed that labeled vagal sensory terminals related to myenteric ganglia were mostly large, mitochondria-rich profiles located predominantly on the surface of the ganglia. Specialized membrane contacts connected sensory terminals with other unlabeled profiles possibly derived from intrinsic neurons. The polarity of these contacts suggested the vagal sensory terminals to be presynaptic to intrinsic neurons of the myenteric ganglia. A hypothesis is formulated postulating a mechanoreceptive role for 'myenteric' vagal sensory terminals, providing both the brainstem (via the vagus nerve) and, by synaptic action upon intrinsic neurons, the myenteric plexus with information on tension and motility of the esophagus and cardia.

Correlative light and scanning electron-microscopic study of feline gastric mucosa: the cardiac region (pars cardiaca).

The cardiac region (pars cardiaca) of the cat's stomach was examined with light and scanning electron microscopy. The glands are simple, coiled tubular, and contain mucus-secreting cells. Their surfaces are covered with microvilli which are concentrated on the boundaries of the mucus-secreting cells. A few cells interposed between the glandular cells are probably G cells. They are identified by apical projections of long microvilli into the lumen of the gland. The surface epithelial cells lining the cardiac region are covered by minute microvilli. The muscularis mucosae is not distinctly divided into two layers. However, a group of smooth muscle cells which are directed in a circular manner around the gastroesophageal junction is considered to be the distal esophageal sphincter.

Endocrine cells in human cardial glands.

The presence of argentaffin cells (possibly of endocrine nature) in the human cardiac mucosa has been reported. The nature of these cells has not been characterized further. Biopsies of cardiac mucosa taken immediately distal to esophageal epithelium were studied ultrastructurally and immunohistochemically in seven healthy volunteers. Of 62 ultrastructurally-examined endocrine cells 21 % were enterochromaffin cells (EC) of the gastric type, 13 % were enterochromaffin (EC2) cells, 56% were enterochromaffin-like (ECl) cells and 10 % were D1 cells. All endocrine cells studied were of the "closed" type, which never reached the lumen of the cardiac glands, being separated from the lumen by the cytoplasm of mucous cells. Immunohistochemical examinations were performed using antibodies to gastrin, glucagon, somatostatin, VIP, secretin, motilin, pancreatic polypeptide, insulin and substance Pl Studies were performed simultaneously on human pancreatic, pyloric and duodenal tissue. Positive reactions were obtained for all antibodies on human tissue. Cardiac glands endocrine cells gave negative reactions for all hormones studied. In conclusion, human cardiac mucosa contains a relatively large number of endocrine cells. The function of these cells remains to be determined.

The endocrine cells of the bovine cardiac glands.

The research is carried on cardiac glands region of the abomasum of the bull by both descriptive and cytochemical ultrastructure. The propose is to compare the present results on this gastric zone to those previously obtained in the other zones of bovine abomasum and the few data referred by other workers in monogastrics. The endocrine cells (Diffuse Neuroendocrine System) identified are in type and order of frequency: EC, ECL, X, D, D1 and these results correspond to those of the proper gastric glands region in the same species. In addition, their lack in luminal connection and their peculiar relationship with the parietal cells is similar in the two zones. On the other hand, a full comparison with monogastrics is not yet possible because analogous studies on the cardiac glands of other species are sparse.

Scanning electron microscopy of Gasterophilus intestinalis lesions of the equine stomach.

The lesions caused by larvae of Gasterophilus intestinalis in the cardiac region of the equine stomach were funnel-shaped ulcers surrounded by a rim of hyperplastic epithelial cells. Bacteria were commonly seen on the rim of epithelial cells, at the base of some ulcers, and within the cavities produced by the hooks of the larvae. Cellular debris and mucus were within the ulcer.

The cells of the rat gastric groove and cardia. An ultrastructural and carbohydrate histochemical study, with special reference to the fibrillovesicular cells.

The distal wall of the groove between the rat forestomach and glandular stomach is lined with a special type of columnar cells (CCGG) and with fibrillovesicular cells (FVC). The cardiac glands contain cardiac mucosa (CMC) and serous cells (CSC). The CCGG contain small mucous granules and special vesicles and tubules. The CMC are filled with large mucous granules and resemble mucous neck cells. The CSC are filled with large proteinaceous granules. The FVC are characterized by long microvilli, apical bundles of microfilaments and a complex "tubulovesicular system". The pattern of 3H-thymidine incorporation and the presence of immature and transitional forms indicate a possible origin of all the cell types concerned from a common undifferentiated precursor. The membranes of the tubulovesicular system of FVC as well as the apical cell membrane were reactive to Thiéry's carbohydrate stain. However, lanthanum tracing of the extracellular space and ultrastructural stereoscopy did not reveal a permanent continuity between both membrane systems. The absence of 3H-thymidine label showed that FVC were not proliferative. The structural characteristics of FVC do not account for a secretory, resorptive or receptive function. The special arrangement of microfilaments and the tubulovesicular system suggests an ability to fast changes in surface area.

The structure of the cells lining the stomach of the tammar wallaby (Macropus eugenii).

The stomach of the tammar may be divided into cardiac, "oesophageal", fundic and pyloric regions. In the cells of the cardiac region (which occupy 65% of the stomach) at least three types of mucous droplet are present. The stratified squamous "oesophageal" region occupies 20% of the stomach and the fundic and pyloric regions make up the remaining 15%. The cellular structure of the three last named regions seems to be similar to that described for other monogastric mammals. Endocrine cells were found in all glandular regions.