Microscopic organization of epithelial endocrine cells of the gastrointestinal tract mucosa in lower vertebrates. II. Epithelial endocrine cells of the duodenum of the common frog

The endocrine epithelium cells of the frog duodenum mucosa were studied using light and electron microscopy. In the intestinal epithelium endocrine cells are distributed among enterocytes all over the surface of mucosa. The greatest quantity of them is observed in the intestinal part in the proximity of the stomach. Six types of endocrine cells are identified on the basis of their granular structure and size. Some differentiation in submicroscopic organization of endocrine cells depending on their functional condition is defined.     

Incorporation of influenza virus M-protein into liposomes.

M-protein from influenza virus vaccine was purified by sodium dodecyl sulfate-gel chromatography and incorporated into liposomes by solubilization with octylglucoside and subsequent dialysis. Liposomes containing M-protein formed a distinct population with a density of 1.22 g/ml on sucrose-gradient centrifugation, regardless of the net charge on the liposomes. Treatment of the liposomes by freeze-fracture followed by electron microscopic examination showed multilamellar structures in those liposomes without M-protein; liposomes containing M-protein were mulberry-like structures which appeared unilamellar. These studies show incorporation of M-protein into the lipid bilayer.     

解脲支原体对兔输卵管黏膜上皮细胞致病性研究

目的：探讨解脲支原体(UU)对兔输卵管黏膜上皮细胞的粘附及其致病性。方法：采用雌性大白兔作为实验对象,用UU感染兔输卵管黏膜上皮细胞,经光学和电子显微镜观察UU对其粘附性和致病性。结果：UU感染后,兔输卵管管腔有较多渗出物,呈淡红染匀质状,黏膜层的上皮细胞轻度肿胀,黏膜下层有炎症细胞(以淋巴细胞为主)呈灶性浸润;在电镜下,UU粘附于输卵管黏膜上皮细胞上,同时上皮细胞游离面的纤毛互相粘连、倒状,纤毛细胞核膜欠完整．胞核染色质呈凝块状．胞浆内可见大量大小不等的空泡,无纤毛细胞顶面参差不齐,可见伪足样突出．微绒毛减少．胞浆内近细胞顶部有少量分泌颗粒和空泡变性,细胞间可见相嵌连接。结论：UU到达兔输卵管后可粘附于输卵管黏膜上皮细胞上并导致损伤。     

Nasal lymphoid tissue in the rat

Summary The structure and organization of paired lymphoid tissue in the nasal mucosa, situated in the transitional zone on both sides of the septal opening to the pharyngeal duct, of conventionally-housed rats was examined by light microscopy and scanning and transmission electron microscopy. Each lymphoid structure consisted of follicles containing T- and B-cell areas, and was covered with specialized epithelium. This epithelium consisted of cuboidal ciliated cells with oval nuclei parallel to the basal lamina. Goblet cells were sparse. Occasionally, islands of microvilli-bearing cells (so called membraneous or M cells) covered the lymphoid structures. M Cells were also found as single cells among the ciliated cells. The morphological characteristics and the particular localization justify the conclusion that the nasal lymphoid tissue described belongs to the mucosa-associated lymphoid tissue. It is therefore suggested that this nasal structure be designated nasal lymphoid tissue.     

Evidence for a role of the monoclonal antibody E48 defined antigen in cell-cell adhesion in squamous epithelia and head and neck squamous cell carcinoma

Monoclonal antibody (MAb) E48 recognizes a 20- to 22-kDa antigen expressed by human squamous and transitional epithelia and their neoplastic counterparts. Histochemical examination of these tissues revealed distinct surface labeling with MAb E48. To investigate the subcellular localization of the E48 antigen we have performed electron microscopical analysis. In cells of normal oral mucosa, the E48 antigen was expressed on the plasmalemma, particularly associated with desmosomes, suggesting involvement of the E48 antigen in intercellular adhesion. Furthermore, the level of expression of the E48 antigen appeared to be influenced by the cellular organization. In squamous cell carcinoma (SCC) cell lines grown in vitro as subconfluent monolayer cultures, the E48 antigen expression was low. However, E48 antigen expression increased when SCC cells were grown to confluency. E48 antigen expression was similarly high when SCC cell lines were cultured under conditions promoting three-dimensional growth either as colonies within floating collagen gels or as xenograft in tumor-bearing nude mice. Further evidence for the involvement of the E48 antigen in cell-cell adhesion was found when SCC cells were grown within collagen gels in the presence of MAb E48: no spherical colonies were formed, but cells grew out to colonies composed of single cells. Moreover, in this culture system the percentage of SCC cells growing out to colonies was decreased by the presence of MAb E48. These findings indicate that the E48 antigen is involved in the structural organization of squamous tissue and might have a role in intercellular adhesion.     

Comparative studies of follicle cells in testes of Glyptocephalus stelleri and Pleuronectes pinnifasciatus (Teleostei, Pleuronectidae)

Accessory cells were studied in early spermatogenesis of flatfishes Glyptocephalus stelleri and Pleuronectes pinnifasciatus using transmission electron microscopy. The morphological organization of accessory cells in G. stelleri was similar to that of Sertoli cells. In P. pinnifasciatus, these cells had morphological organization, which had not been previously described.     

Taenia taeniaeformis: Increased cell growth and neutral mucus production in the gastric mucosa of the rat with a larval infection

Gross hyperplasia of the gastric mucosa and excessive mucus production in the stomach occur in rats heavily parasitized with larvae of Taenia taeniaeformis. In this study, a positive correlation between the number of larvae recovered from hepatic cysts and the weight of the stomachs of infected rats was found. By light microscopy, the hyperplasia was restricted to the glandular mucosa. Parietal and chief cells were very rare, and densely PAS-positive mucous cells were the major cell types in the hyperplastic stomach while, in comparison, alcian blue-positive cells were much fewer in number. The isolated gastric mucosa in organ culture had an increased [³H]thymidine incorporation rate in rats infected with T. taeniaeformis. The hexosamine concentration per milligram protein in the hyperplastic stomach mucosa was twice that in the control rat stomach mucosa. By electron microscopy, the apical cytoplasm of the mucous cells was found to be filled with small dark granules. These results indicate that the gastric hyperplasia is caused by stimulation of growth and major differentiation of stem cells to neutral mucus-producing cells.     

Immunocytochemical localization of ornithine transcarbamylase in rat intestinal mucosa. Light and electron microscopic study

We investigated light and electron microscopic localization of ornithine transcarbamylase (OTC) in rat intestinal mucosa. In the immunoblotting assay of OTC-related protein, a single protein band with a molecular weight of about 36,500 is observed in extracts of liver and small intestinal mucosa but is not observed in those of stomach and large intestine. For light microscopy, tissue slices of the digestive system were embedded in Epon and stained by using anti-bovine OTC rabbit IgG and the immunoenzyme technique. For electron microscopy, slices of these and the liver tissues were embedded in Lowicryl K4M and stained by the protein A-gold technique. By light microscopy, the absorptive epithelial cells of duodenum, jejunum, and ileum stained positively for OTC, but stomach, large intestine, rectum, and propria mucosa of small intestine were not stained. Electron microscopy showed that gold particles representing the antigenic sites for OTC were confined to the mitochondrial matrix of hepatocytes and small intestinal epithelial cells. However, the enzyme was detected in mitochondria of neither liver endothelial cells, submucosal cells of small intestine, nor large intestinal epithelial cells. Labeling density of mitochondria in the absorptive epithelial cells of duodenum, jejunum, and ileum was about half of that in liver cells.     

Endocrine cells in gastric carcinoma and adjacent mucosa. An immunohistochemical and ultrastructural study

Endocrine cells are often found in human gastric carcinoma and may be recognized by the immunoreactivity of their chromogranin A, peptides and biogenic amines content. Anti-chromogranin A was used to investigate the morphology of endocrine cells using light and electron microscope immunohistochemical techniques. The hormone content of endocrine cells was examined in both tumour tissue and tumour-adjacent mucosa. It was found that the endocrine cells in tumour tissue were malignant, often had amphocrine differentiation and did not resemble a normal cell type. The hormone content of endocrine cells in tumour tissue seldom corresponded to the hormonal content of endocrine cells in tumour-adjacent mucosa. In intestinal-type carcinoma and in some parts of diffuse-type gastric carcinomas, endocrine cell hyperplasia and an alteration of the differentiation in the tumour-adjacent mucosa were discovered. The distribution of endocrine cells in the tumour tissue was different in both types of gastric carcinoma. The results reported here suggest that endocrine cell differentiation of malignant endocrine cells in human gastric carcinoma develops in a different way from that of endocrine cells in tumour-adjacent mucosa, and as a result, diverse hormonal products may appear in tumour tissue.     

Experimental infection of young broiler chicks with Treponema hyodysenteriae

In young broiler chicks which were inoculated with 10(8) cells of Treponema hyodysenteriae within 24 hr after hatching, numerous treponemes were observed by scanning electron microscopy on the surface of the cecal mucosa 7 and 14 days after the inoculation. However, in the groups inoculated with 10(7) cells, treponemes were not observed on the cecal mucosa 14 days after the inoculation, and the isolation rate from the cecal contents was lower than that from cecal contents of chicks inoculated with 10(8) cells. While the cecal mucosa of noninfected chicks had a smooth surface, that of the chicks infected with treponemes was generally roughened and the epithelium was eroded. Numerous treponemes were also observed within the eroded epithelium.     

'Pear-shaped' cells in the digestive tract of the perch Percafluviatilis (L.)

Light and electron microscopy revealed the presence of 'pear-shaped' cells amongst the mucosal cells of the stomach, pyloric curvature, pyloric caeca and the anterior-most region of the intestines of perch. The cells are usually located in the distal region of the mucosa and are approximately half the height of the other mucosal cells. Electron microscopy shows that the cells are composed of thick outer sheaths which are fibrillar in appearance. The cytoplasm is characterized by electron dense rods numbering from three to fifteen, which originate from the supranuclear region of the cells and converge apically. The rest of the cytoplasm is composed of Golgi apparatus, secretory vacuoles, minute mitochondria and a network of cytoplasmic strands laden with ribosomes. The organization of organelles in these cells does not resemble that of other mucosal cells of the alimentary canal. Contrary to what has been suggested previously, the 'pear-shaped' cells neither resemble nor represent stages in the formation and maturation of goblet cells.     

'Pear-shaped' cells in the digestive tract of the perch Perca fluviatilis (L.)

Light and electron microscopy revealed the presence of 'pear-shaped' cells amongst the mucosal cells of the stomach, pyloric curvature, pyloric caeca and the anterior-most region of the intestines of perch. The cells are usually located in the distal region of the mucosa and are approximately half the height of the other mucosal cells. Electron microscopy shows that the cells are composed of thick outer sheaths which are fibrillar in appearance. The cytoplasm is characterized by electron dense rods numbering from three to fifteen, which originate from the supranuclear region of the cells and converge apically. The rest of the cytoplasm is composed of Golgi apparatus, secretory vacuoles, minute mitochondria and a network of cytoplasmic strands laden with ribosomes. The organization of organelles in these cells does not resemble that of other mucosal cells of the alimentary canal. Contrary to what has been suggested previously, the 'pear-shaped' cells neither resemble nor represent stages in the formation and maturation of goblet cells.     

Endocrine cells in the gastric mucosa of elasmobranch fishes. An ultrastructural study

The endocrine cells of gastric mucosa of two elasmobranch species were studied by light and electron microscopy. Five cell types were identified in the fundic mucosa, four of which are of "open type". All of them show pleomorphic granules of variable size, except those of the type V cell which are round in shape and of comparatively small diameter. Six different cell types are found in the pyloric mucosa, all of "open type" except for type XI cells which appear to be "closed". Pyloric types VIII, IX, X and XI cells show similar structural characteristics as fundus types I, V, II and IV respectively. Silver impregnation was also used at both light and electron microscopical levels. No functional classification or analogies with other vertebrate gastric endocrine cells were attempted as these would be too speculative on the basis of ultrastructural characteristics only.     

优势菌群失衡对肠黏膜上皮结构的损害

目的通过观察小鼠肠道优势菌群失衡肠黏膜上皮结构的变化以探讨肠道优势菌群失衡对黏膜机械屏障的影响。方法利用光镜及电镜技术观察轻度、重度菌群失衡小鼠肠道黏膜绒毛形态变化及上皮细胞超微结构的变化。结果菌群失衡小鼠肠黏膜绒毛出现肿胀、断裂,绒毛顶端肠上皮细胞坏死、脱落,重度菌群失衡与轻度菌群失衡小鼠比较绒毛结构受损加重。超微结构观察发现上皮细胞间隙增宽,胞浆内出现空泡结构,黏膜及黏膜下层有淋巴细胞浸润。结论抗生素干扰肠道优势菌群,可导致肠道机械屏障黏膜绒毛及超微结构受损且重度优势菌群失衡的损害大于轻度优势菌群失衡的损害。     

Light and electron microscopic identification of several types of endocrine cells in the gastrointestinal mucosa of the cat

Summary The following histological methods, previously proved to be useful in selective light microscopic detection of endocrine cells, were applied to the cat gastrointestinal mucosa: for the identification of biogenic amines, diazonium, ammoniacal silver and xanthydrol methods; for granules identification, methyl green-red acid dyes, toluidine blue, HCl-basic dye, lead-haematoxylin, phosphotungstic haematein and argyrophil methods. Results were compared with those of an extensive electron microscopic investigation.Five types of endocrine cells were identified in the gastric mucosa. Three types were found in the pyloric mucosa: the previously described 5-hydroxytryptamine-producing enterochromaffin cell, the gastrin producing G cell and a cell with an unknown function, labelled in this paper the X cell. Four types were found in the fundic mucosa: enterochromaffin cells (rarely observed), enterochromaffin-like cells secreting a 5-hydroxyindole but showing some ultrastructural and staining differences from true enterochromaffin cells (numerously present), A-like cells (few), resembling A cells of the pancreatic islets, and X cells, resembling those in the pyloric mucosa.In the intestinal mucosa, at least three endocrine cell types were distinguished in its duodenal part: enterochromaffin cells and two types of polypeptide-producing cells — some with smaller granules (S cells) and others with larger granules (L cells). Only two types were found in the mucosa of terminal ileum: enterochromaffin cells and numerously-occurring cells with large granules resembling in part duodenal L cells. The possibility of a relationship between S and L cells and the production respectively of the intestinal hormones secretin and cholecystokinin-pancreozymin was discussed.This investigation was supported by a grant N. 115/1139/0/4715 of the Italian Consiglio Nazionale delle Ricerche.     

Immunological importance of the second gut segment of carp.

Lymphocytes, plasma cells, granulocytes (three to four types), macrophages and monocyte-like cells were ultrastructurally distinguished in the intestinal mucosa of carp. Neutrophilic granulocytes and lymphoid cells were present in and under the epithelium throughout the gut. In contrast to macrophages which dominated in the epithelium of the second segment, basophilic and eosinophilic granulocytes (and their intermediates) were mainly found in the connective tissue of the first segment. Applying monoclonal antibodies against serum immunoglobulin (Ig) in an immunogold technique, only a minority of lymphoid cells appeared to be Ig-immunoreactive at their external membrane, suggesting the presence of many more T than B cells in the intestinal mucosa. Except for cells which resembled immature plasma cells, plasma cells did not show, or hardly showed, Ig at their surface. In contrast with the head kidney, plasma cells with an Ig-immunoreactive cytoplasm were scarce in the intestinal mucosa. As mucosa plasma cells were regularly found with the electron microscope, they possibly contain another class of Ig. Macrophages and monocyte-like cells were also found to be Ig-immunoreactive, suggesting the presence of immune complexes at their external membrane. The immunological significance of B- and T-like lymphocytes next to immune complex-binding and antigen-presenting macrophages in the second gut segment is discussed.     

Self-renewal of the human gastric epithelium: new insights from expression profiling using laser microdissection

The gastric mucosa is subject to continual bidirectional renewal by differentiation from stem and transit amplifying cells. It was the aim of this study to characterize the self-renewal of the human gastric mucosa and its two major types of glands in the fundus and antrum, respectively. Three characteristic regions (pit, proliferative, and lower neck regions) were isolated from fundic and antral units by the use of laser microdissection, and expression profiles concerning 15 marker genes were generated by RT-PCR analysis. The surface mucous cells (SMCs) of fundic and antral units differed in their expression of at least four secretory genes, i.e., gastric lipase, TFF3, FCGBP, and lysozyme. The maturation of mucous neck cells was shown to occur stepwise, first towards a mucous phenotype followed by a serous differentiation step. Also, a stepwise maturation of both the antral SMCs and antral gland cells was observed. Additionally, the presence of gastric lipase was also demonstrated for the first time in antral gland cells. In conclusion, the different expression profiles of SMCs of the fundic and antral units could be the basis for the different self-renewal rates of fundic and antral SMCs and could influence the spatial organization of the bacterial microbiota within the various parts of the gastric mucosa.     

Ultrastructural changes in the oviductal mucosa throughout the sexual cycle in Bufo arenarum

In Bufo arenarum the oviduct exhibits conspicuous changes throughout the sexual cycle. In the present study, we analyzed the optical and ultrastructural characteristics of the oviductal pars convoluta mucosa, the portion responsible for jelly secretion, during both the preovulatory and postovulatory periods. Secretory epithelial cells, ciliated cells, basal cells, and glandular cells are described. Secretory epithelial cells are characterized by the presence of secretory granules, the size, shape and electron density of which vary markedly. Their contents are mainly released by exocytosis into the oviductal lumen. Moreover, in the preovulatory period, apocrine, and holocrine secretion processes frequently occur. During the postovulatory period, these cells exhibit a marked diminution of secretory granules. Ciliated cells show a typical ultrastructural organization. Basal cells are distinguished in the lower part of the epithelium by their heterochromatic nuclei and electron‐lucent cytoplasm. These cells, to the best of our knowledge, are reported for the first time in Amphibia. Glandular cells exhibit oval, round, or polyhedric granules, most of them with one or more cores. Our results indicate that the contents of epithelial and glandular secretory cells are partially secreted during the preovulatory period. Additional secretion occurs during the transit of the oocytes. J. Morphol. 239:61–73, 1999. © 1999 Wiley‐Liss, Inc.     

Regeneration of endocrine cells in the stomach

A mucosal defect was produced by cryosurgery in the antral and the fundic wall of the rat stomach, and regeneration of gastric endocrine cells was studied 50, 100 and 200 days after operation. Fifty days after the operation, the mucosal defect was completely covered with regenerated epithelium. The regenerated mucosa both in the antral and in the fundic region consisted of mucinous glandular structures. The regenerated mucosa in the corpus remained pseudopyloric in type even 200 days after operation. Regardless of the time after operation, regeneration of endocrine cells was always observed. We could identify G cells and EC cells in the regenerated mucosa of the antrum, and EC cells, A cells and AL cells in the regenerated mucosa of the corpus, respectively. By electron microscopy, endocrine-exocrine cells were frequently encountered. These cells had two different types of intra-cytoplasmic granules; one was an endocrine-specific, small electron-dense granule, and the other a large, lucent mucin droplet-like granule. These findings indicate that the endocrine cells of the stomach are formed from endodermal precursor cells.     

Enzyme-ultracytochemical study of adenylate and guanylate cyclases in normal and pathologic human nasal mucosa

The ultracytochemical localization of adenylate cyclase (AC) and guanylate cyclase B (GC-B) and C (GC-C) activity was studied after stimulation with pituitary adenylate cyclase activating peptide, C-type natriuretic peptide and guanylin, respectively, in normal human respiratory nasal mucosa and mucosa of nasal polyps. To demonstrate these enzymatic activities, we employed enzyme-ultracytochemical methods for electron microscopy. Both normal and pathologic nasal mucosa contained AC, GC-B and GC-C activity. In the upper portion of respiratory epithelium, the enzymes were detected on ciliary and microvillar membranes. In ciliary membranes, GC-B was the predominant form expressed. In goblet cells and in glands of the lamina propria, enzymatic activities were localized mainly on plasma membranes and on membranes lining secretory granules. The results did not reveal any evident differences between the enzymatic activities in normal and pathological nasal mucosa and suggest complementary activities for these enzymes and their stimulators in the regulation of mucociliary transport and glandular secretion.