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O Ohtani

Publications and source records attributed to O Ohtani.

At least 37 records · Page 2Linked to original sources
PubMed1995

Scanning electron microscopic studies of reticular framework in the rat mesenteric lymph node.

BACKGROUND: The reticular framework in the lymph node has in the past been studied mainly by light microscopy of silver-impregnated specimens. The aim of the present study is to understand three-dimensionally the ultrastructure and organization of the reticular framework better than before. METHODS: The mesenteric lymph nodes of the rat were prepared either an alkali-water maceration method or a conventional method and were observed in a scanning electron microscope (SEM). RESULTS: The SEM study of alkali-water macerated tissues visualized directly the reticular fiber network in the lymph node. The reticular fibers consisted of thin bundles of collagen fibrils. They were continuous with the collagen fibrillar sheaths of blood vessels and lymphatic sinuses as well as with the fibrous capusule, thus acting as a skeleton of the lymph node. The arrangement of the reticulum was variable, depending on individual compartments. The SEM study of conventionally treated tissues, on the other hand, clarified the shape of reticular cells and their relationship with the reticular fibers. The sinus reticular cells connected with the sinus lining cells but separated from the parenchymal reticular cells, indicating that the former two originate from lymphatic endothelial cells. The parenchymal reticular cells varied in shape depending on their locations but essentially shared features with fibroblasts. CONCLUSIONS: The arrangements of the reticular fibers in the parenchyma were closely related to the associated reticular cells, showing the possibility that the reticular cells maintain the shape of the reticular framework suitable for each compartment of the lymph node.

Animals↗
PubMed1995

Microanatomy of the rat diaphragm with special reference to the lymphatics and mesothelial stomata.

The three-dimensional microstructure of the rat diaphragm was studied in order to reveal morphological bases which permit peritoneal fluids to pass across the diaphragm to enter the pleural cavity. The methods used include scanning electron microscopy of either intact or alkali-treated tissues, enzyme-histochemistry, and confocal laser scanning microscopy (CLSM). The peritoneal and pleural surfaces of the diaphragm are covered with mesothelial cells studded with numerous microvilli. There are many round gaps between mesothelial cells on the peritoneal side of the diaphragm. The subperitoneal connective tissue contains voluminous, irregularly shaped lymphatics which extended many funnel-shaped projections of the endothelia towards the pored region of the mesothelium. On coming into contact with the mesothelium, many of the lymphatic projections are perforated at their ends, thus giving rise to stomata connecting the peritoneal cavity and lymphatic lumen. Some projections ended blindly while plugging the mesothelial pores, thereby making visible some intercellular gaps in this contact. The subperitoneal sheet of collagen fiber network possesses clusters of pores which tightly fit the passage of the lymphatic projections. CLSM of the diaphragm after intraperitoneal injection of FITC-dextran has demonstrated the tracer both in the lymphatic lumen and in the connective tissue spaces. The tracer has also been detected in the lymphatics located in the subpleural connective tissue space. These results indicate that peritoneal fluid is allowed to flow into the lymphatics directly through the stomata and indirectly through the intercellular gaps between endothelia and mesothelial cells, and then drain into the subpleural lymphatics. Discussions were made on the probable mechanisms by which a hydrothorax may occur during continuous ambulatory peritoneal dialysis.

Animals↗
PubMed1994

Three-dimensional microvasculature of the hair follicle.

The three-dimensional microvasculature of the hair follicle of the adult Wistar rat was demonstrated by scanning electron microscopy of vascular corrosion casts. The anagen hair follicle was surrounded by the basket-like capillary network which was supplied by the branches of the subcutaneous artery and drained into the veins continuous with the subcutaneous vein. The capillary network surrounding the anagen hair follicle was most dense at its bottom, and became sparse at its upper part. The telogen hair follicle was surrounded by only a few capillaries. Transmission electron microscopy showed that the capillaries around the hair bulb possessed fenestrations. Our results indicate that the microvasculature of the anagen hair follicle is so organised as to supply the hair bulb with abundant blood, which is the most important area for hair growth.

Animals↗
PubMed1993

Microanatomy of the rat diaphragm: a scanning electron and confocal laser scanning microscopic study.

The present study demonstrated the three-dimensional microstructure of the rat diaphragm by scanning electron microscopy (SEM) of either intact or alkali-treated tissues, enzyme-histochemistry, and confocal laser scanning microscopy (LSM). The peritoneal and pleural surfaces of the diaphragm were covered with mesothelial cells studded with microvilli. Many round gaps were formed between the mesothelial cells. The submesothelial connective tissue contained voluminous, irregularly shaped lymphatics. Some of these lymphatics extended many funnel-like projections of their endothelia towards the pored region of the mesothelium. On coming into contact with the mesothelium, many of the lymphatic projections were perforated at their ends, thus giving rise to stomata connecting the peritoneal cavity and lymphatic lumen. Some projections ended blindly while plugging the mesothelial pores, thereby making visible some intercellular gaps in this contact. The subperitoneal sheet of the collagen fiber network possessed clusters of foramina which tightly fit the passage of the lymphatic projections. Confocal LSM of the diaphragm after intraperitoneal injection of FITC-dextran demonstrated the tracer both in the lymphatic lumina and in the connective tissue spaces. Our results indicate that peritoneal fluid is allowed to flow into the connective tissue spaces of the diaphragm through intercellular gaps and into lymphatics through stomata.

Animals↗
PubMed1992

Structure of lymphatics in rat cecum with special reference to submucosal collecting lymphatics endowed with smooth muscle cells and valves. I. A scanning electron microscopic study.

The three-dimensional structure of lymphatic vessels in the rat cecum was studied by KOH-collagenase digestion/scanning electron microscopy (SEM), and corrosion casting/SEM. Abluminal surfaces of the lymphatic vessels show flat elliptical nuclear regions and flat cytoplasmic processes interdigitated with adjacent ones. The lymphatic capillaries closed by interdigitations of flat endothelial processes at their initial portion begin at the various levels of the mucosa. They descend and pass through the muscularis mucosa to connect with the lymphatic vessels in the submucosa. They form polygonal meshwork, the distances between intersections being about 0.2-0.5 mm. They also have valves, the distances between adjacent valves being about 0.1-0.6 mm. Most of the submucosal lymphatic vessels are surrounded by either periendothelial cells or typical smooth muscle cells. The polygonal meshworks made up of stellate periendothelial cells with many irregular processes embrace the initial segment of the collecting lymphatics. As they proceed proximally, the periendothelial cells become elongated and branch out by threes or fours, thus presenting the appearance of smooth muscle cells. These branches are connected side by side and run obliquely along the vessels, thus forming polygonal meshworks around the vessels. The more proximal collecting lymphatic vessels are surrounded by circularly oriented smooth muscle cells. Our results indicate that most of the lymphatic vessels in the submucosa are collecting ones and possess smooth muscle cells as well as valves. This suggests that the lymphatic vessels in the submucosa actively contract and propel the lymph towards the mesenteric lymphatic vessels.

Animals↗
PubMed1992

The maceration technique in scanning electron microscopy of collagen fiber frameworks: its application in the study of human livers.

This paper reviews the cell-maceration/scanning electron microscopic (SEM) technique and its application in the study of human livers. The maceration of glutaraldehyde-fixed tissues with 2N-NaOH and water at room temperature effectively and consistently removes all the cells, thus exposing collagen fiber networks. SEM of the macerated tissues shows three-dimensional arrangements of collagen fibers more clearly than previously reported methods. High resolution SEM observations of macerated and non-macerated collagen fibrils of the rat tail tendon have revealed that both show similar cross-striated bandings that are determined by an alternate succession of elevated and depressed segments along the collagen fibrils, with a period of approximately 65 nm. Three ridges have been observed in the nonmacerated collagen fibrils: two on the margins of the elevated segments and one at an intermediate point of the depressed segment. The macerated collagen fibrils show a straight arrangement with slightly wavy microfibrils. The subendothelial spaces of Disse in the human liver contain abundant collagen fibers. There are some collagen fibers that stretch between adjacent collagen fiber sheaths in the subendothelial spaces of Disse, either forming a mono-layered network or coursing individually. The collagen fibers in the spaces of Disse are continuous with those in the liver capsule and in the Glisson's sheaths and with those around the central and sublobular veins. The collagen fibers in human livers form a network of the liver as a whole, thus constituting a hepatoskeletal system.

Aged↗
PubMed1991

Organization of the reticular network of rabbit Peyer's patches.

The organization of the network of collagen fibers of rabbit Peyer's patches was examined by scanning electron microscopy (SEM) in alkali-water macerated tissues. The relationship between this network and the reticular cells within it was further studied by SEM of ultrasonicated tissues. Collagen fibrils (about 60 nm in diameter) formed collagen fibers or sheets. There were sheets of collagen fibrils with numerous pores beneath the patch dome epithelium. Within the patches, collagen fibers repeatedly divided and fused, forming the reticular network. The reticular network within the follicle was looser than within the dome, the corona, or the interfollicular area. The latter three compartments showed similar structures and consisted of numerous intercommunicating small subcompartments. Reticular cells were in contact with groups of free cells lodged in these subcompartments within the reticular network. Reticular cell processes with numerous fenestrations embraced not only collage fibers forming the reticular network, but also sheaths of collagen fibers of blood and lymphatic vessels. Sheaths of collagen fibers of high endothelial venules and lymphatic vessels were also fenestrated, indicating the sites through which lymphocytes and other free cells migrate. These results indicate that the reticular network of Peyer's patches is organized so as to facilitate migration and lodging of free cells and thus facilitate antigen-to-cell and cell-to-cell interactions during an immune response. The naked areas on the collagen fibers seem to provide a scaffolding for free cells during their migration.

Animals↗
PubMed1991

Three-dimensional organization of the collagen fibrillar framework in the rat adrenal gland.

The three-dimensional organization of the collagen fibrillar framework in the rat adrenal gland was studied using an alkali-water maceration method and scanning electron microscopy. The structure thus obtained was a continuum of collagen fibril plexuses extending through the adrenal capsule, cortex and medulla. The capsule consisted of finely meshed collagen fibril sheaths and layered, coarsely meshed plexuses of bundles of collagen fibrils. In the cortex, the channels of cortical capillaries were surrounded by thin sheaths of collagen fibrils. Many slender bundles of collagen fibrils extended from these sheaths into intercellular spaces and interconnected adjacent pericapillary sheaths. The collagen fibril sheath tubes precisely reflected the cortical blood vascular architecture; thus the three cortical zones--zona glomerulosa, zona fasciculata and zona reticularis--were also clearly remarked. In the medulla, collagen fibrils were interwoven into more tightly meshed sheaths around the peripheral radicles and venous tributaries of the central veins. Basket-like collagen fibril sheaths divided the spaces among these tree-like perivascular collagen fibril sheath tubes into round compartments which, in intact tissues, contained chromaffin cell nodules and nervous elements. Small tube-like spaces for housing the medullary capillaries were located in the interstices of contiguous collagen fibril baskets. Besides supporting the organization of the gland, the collagen fibrillar framework in the adrenal gland is believed to play important roles in providing three-dimensionally elaborated extravascular spaces for the diffusion of metabolites and physiological messengers, including hormones.

Adrenal Cortex↗
PubMed1991

Measurements of the auricle in the human fetus.

The auricular length, auricular base length and auricular width were measured in 94 human fetuses with crown-rump (CR) lengths ranging from 49 mm (approximately 11 weeks of gestational age) to 250 mm (approximately 31 weeks of gestational age). The three measurement values showed linear increases as the CR length increased, suggesting that they are useful parameters to indicate intrauterine growth. The measurement values also suggested that the mandibular and hyoid derivatives did not grow independently, but did grow with maintaining a certain relationship.

Anthropometry↗
PubMed1990

Vascular pattern of the guinea pig tympanic membrane.

The vascular organization of the guinea pig tympanic membrane was studied by light microscopy in India-ink-, colored-gelatin-, or horseradish peroxidase (HRP)-injected specimens. The ultrastructural localization of the vessels was examined by transmission electron microscopy in HRP-injected material. We found that the tympanic membrane is supplied by two arterial sources, the superior and inferior tympanic arteries, both of which arise from the posterior auricular artery. The superior tympanic artery gives off arterioles which, in the tympanic membrane, run centrifugally from the attachment of the manubrium, while the inferior tympanic artery emits arterioles which run centripetally from the tympanic annulus. Both sets of arterioles divide into capillaries and form a monolayered polygonal meshwork. The capillaries drain into venules which run between arterioles in the membrane and empty into either the superior tympanic vein located at the manubrium or the inferior tympanic vein at the annulus.

Animals↗
PubMed1990

Ultrastructures of the epithelial basement membrane and the subepithelial capillaries in rabbit palatine tonsils.

The ultrastructure of both the epithelial basement membrane and the subepithelial capillaries in rabbit tonsils was investigated using light and transmission electron microscopy of sections, and scanning electron microscopy of alkali-water macerated tissues. The basement membrane of the crypt epithelium was seen to consist of the lamina lucida, lamina densa and lamina fibroreticularis. The lamina fibroreticularis is made up of both fine and thick collagen fibrils. The basement membrane possesses numerous pores (0.5-20 microns in diameter) through which free cells migrate. The basement membrane overlying the follicle protrudes hemispherically towards the crypt lumen, while that over the interfollicular area forms many papillary projections. The capillaries are surrounded by collagen fibrillar sheaths invariably located below the collagen fibrillar sheet of the epithelial basement membrane. The capillaries immediately below the crypt epithelium, including switch-back loops of capillaries in the papillae, are fenestrated sinusoids (20-40 microns in diameter). Plasma cells, lymphocytes and macrophages are numerously gathered around the capillaries. Possible functional relations between these free cells and the fenestrated sinusoids are discussed.

Animals↗
PubMed1990

Organization of the lymphatic vessels and their relationships to blood vessels in rabbit Peyer's patches.

The three-dimensional organization of the lymphatic vessels and their relationship to blood vessels in rabbit Peyer's patches were demonstrated by scanning electron microscopy (SEM) of corrosion casts and of tissues. The interconnected central lacteals in the villi overlying the interfollicular area were connected with the lymphatic plexus in the area. There were many blind-ending lymphatic vessels in the upper part of the interfollicular area. These lymphatics gradually fused and formed perifollicular lymphatic sinuses which surrounded the lateral surfaces and bottoms of the follicles. There were no lymphatic vessels within the dome and the follicle. The perifollicular lymphatic network surrounded the capillary network of the follicle. Between the perifollicular lymphatic networks in the interfollicular area were many high endothelial venules (HEVs) which collected the capillaries in the dome and the follicle. The voluminous perifollicular lymphatic sinuses seemed to have a great potential capacity as both reservoirs and as drainage routes for fluid and lymphocytes. The close association of HEVs with the perifollicular lymphatic vessels seemed to facilitate the prompt drainage of fluid and macromolecules leaking out of HEVs during lymphocyte migration into the lymphatics. That the HEVs are downstream of the capillaries in both the dome and the follicle suggests that substances such as cytokines may be involved in the induction of the post capillary venules into HEVs.

Animals↗
PubMed1989

Microvascular organization of human palatine tonsils.

We describe the three-dimensional organization of the microvasculature of human palatine tonsils as revealed by the vascular corrosion casting/scanning electron microscope method and light microscopy of sections. The tonsillar arteries travel in the connective tissue septa and give off many branches. They further branch into arterioles which in turn enter the follicle and the interfollicular region. These arterioles, giving off capillaries en route, reach the subepithelial region where they break up into sinusoidal capillaries. The subepithelial capillary network overlying the follicle protrudes hemispherically towards the crypt, while that overlying the interfollicular region has many switch-back loops of capillaries projected towards the crypt. The subepithelial sinusoids gather into the high endothelial venules (HEVs) which, collecting capillaries in the follicle and the interfollicular region en route, course down into the interfollicular region alongside the follicle. The HEVs surround the lateral and basal surfaces of the follicle and ultimately lead into the ordinary veins in the septa. The subepithelial sinusoids seem to be involved in taking up immunoglobulins secreted by plasma cells and any other substances released by lymphocytes and/or macrophages as well as supplying the tissues with necessary oxygen and nutrients. That the HEVs are downstream to the subepithelial sinusoids suggests that some substances which are taken up into the sinusoids and transported to the postcapillary venules induce differentiation of HEVs and maintain them.

Humans↗
PubMed1988

Collagen fibrillar networks as skeletal frameworks: a demonstration by cell-maceration/scanning electron microscope method.

A cell-maceration/scanning electron microscope (SEM) method was employed to demonstrate the arrangement of the collagen fibrillar network of various tissues. Immersion of fixed tissues in NaOH (25 degrees C) for 3-7 days, followed by rinsing in distilled water successfully removed the cellular elements, exposing collagen fibrils which were identified as such by transmission electron microscopy in their natural locations. SEM observations of the preparations are able to demonstrate the three-dimensional architecture of collagen fibrils much more precisely than other methods, including the silver impregnation method. Collagen fibrils, forming sheaths for housing individual cardiac myocytes, fused together, thus ensuring an equal stretch of contiguous myocytes and preventing the slippage of adjacent cells. Individual skeletal muscle fibers and nerve fibers were ensheathed by the meshwork of collagen fibrils running in two opposite helices. Such structures seem to play an important role in resisting the stretching impetus. At the epithelial-connective tissue junction of the tongue and fingertip skin, interwoven collagen fibrils formed numerous microridges which probably provide a broad anchorage for the epithelium. In the intestinal mucosa, the collagen fibrillar network immediately below the basal laminae of the villous epithelium possessed heterogeneous pores. As the collagen fibrillar network shows morphological features specific to individual organs and tissues, it is suggested that such formations not only constitute the skeletal framework but also provide those cells which are housed there with a microenvironment suitable for their activities.

Animals↗
PubMed1988

The blood vascular wreath of rat ovarian follicle, with special reference to its changes in ovulation and luteinization: a scanning electron microscopic study of corrosion casts.

Blood vascular casts of rat ovaries were prepared by injection of a low viscosity methacrylate medium, and observed by scanning electron microscopy. The proper vascular pattern of the rat ovarian follicle starts as a basket-like wreath of fine capillaries around the primary follicle. As the follicle grows larger, the wreath becomes more developed. The fully developed wreath around the Graafian follicle consists of sinusoidal capillaries. In ovulation, the apical area of the wreath is opened and the basal area of the wreath is elevated. After ovulation, the wreath shrinks and its opened area is closed, with markedly dilated vessels directly continuous with the arterial capillaries. The wreath then transforms, by intense new formation of capillaries, into a conglomerated sinusoidal capillary plexus with an avascular area within it. The avascular area soon disappears by continued intense formation of capillaries, in the plexus, and a complete and dense vascular network of the corpus luteum is formed. The capillaries of the fully developed corpus luteum are small in caliber and not sinusoidal in nature. Discontinuities of the capillaries and a flattening of the efferent branches are the initial signs of the degeneration of the corpus luteum. The small markedly degenerated corpus luteum contains only scattered thready capillaries. The corpus albicans contains few blood vessels.

Animals↗
PubMed1988

Three-dimensional organization of the collagen fibrillar framework of the human and rat livers.

The collagen fibrillar framework in the human and rat liver was demonstrated by a cell-maceration/scanning electron microscope (SEM) method. Maceration of fixed tissues with alkali plus water successfully removed the cellular elements, exposing collagen fibrils which measured about 60 nm in diameter and were identified as such by transmission electron microscopy (TEM). The normal human liver contained 12.4 mg of collagen fibrils/g of wet tissue, while rat livers contained 1.3 mg of collagen fibrils/g of wet tissue. In the Glisson's sheaths were condensations of collagen fibrils which extended to the hepatic lobules. In the spaces of Disse collagen fibrils ran either solitarily or in bundles and formed sheaths for housing the sinusoids. The central veins and the sublobular veins were also surrounded by the collagen fibrillar sheaths which were continuous with those in the spaces of Disse. Between adjacent sheaths of sinusoids frequently stretched collagen fibrillar bundles which were confirmed by TEM to occur in inter-hepatocellular spaces continuous with the spaces of Disse. The collagen fibrillar layer of the human liver capsule was much thicker (70-100 microns in thickness) than that of the rat liver (less than 5 microns in thickness). The collagen fibrils of the capsule were also continuous with those in the spaces of Disse. The collagen fibrillar framework of the liver is presumed not only to mechanically support the tissue, but also to form a microenvironment for hepatocytes and cells in the Disse's space.

Adult↗
PubMed1987

Three-dimensional organization of lymphatics and its relationship to blood vessels in rat small intestine.

The lymphatic organization and its relationship to the vascular system in the rat small intestine was studied by scanning electron microscopy of corrosion casts and freeze-fractured tissues, and by light microscopy of injected preparations. The villus possessed 3-10 or more central lacteals depending upon the villous width. The lacteals in each villus possessed interconnections between adjacent ones and were surrounded externally by the villous capillary network. At the villous base, the lacteals fused and formed a wide sinus, from which 2 or 3 lymphatics descended and led into the submucosal ones. In the muscularis externa there was a coarse lymphatic network which, together with the submucosal one, drained into collecting lymphatics continuous with the mesenteric ones. The central lacteals and the sinus were lined with thin endothelial cells with cytoplasmic leaves interdigitating with those of adjacent ones. There were tissue channels in the villous interstitial space, which opened through the gaps between the lymphatic endothelial cells into the central lacteals. The voluminous lacteals in the villi suggest their great potential for lymph formation. The existence of collecting lymphatics with valves in the muscularis externa suggests that contraction of the layer is involved in transporting lymph towards the efferent lymphatics.

Animals↗