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Biomedical subjects

A Ohtsuka

Publications and source records attributed to A Ohtsuka.

At least 145 records · Page 8Linked to original sources
PubMed1986

Fine anionic iron colloid and its use in light and electron microscopic detection of cationic sites in the rat kidney.

Ferric chloride, when boiled with ammonium thiocyanate, ammonia and cacodylic acid, is converted into a fine anionic iron colloid which consists of 1-1.5 nm electron dense granules and gives a distinct Prussian blue reaction. This colloid allows light and electron microscopic detection of ionized cationic sites in tissues at a pH range of 4.0-9.0. Light and electron micrographs of the rat kidney stained with this colloid are demonstrated. These micrographs indicate that the foot processes of glomerular podocytes and the brush border of the proximal convoluted tubule contain positively-charged groups in their intracellular matrices, and that the foot process plasma membrane fronting the Bowman's capsular space has positively-charged groups. The latter finding, together with our previous study (Murakami et al., 1986), suggests the co-existence of cationic and anionic sites on this foot process surface.

Animals↗
PubMed1985

Three-dimensional organization of lymphatics and their relationship to blood vessels in rabbit small intestine. A scanning electron microscopic study of corrosion casts.

Casts of small intestinal blood vessels and lymphatics in the rabbit were made with methacrylate and observed under a scanning electron microscope (SEM). In casting the lymphatics, a specially diluted low viscosity medium was injected intraparenchymally into the intestinal submucosa. This parenchymal injection allowed good reproduction of fine lymphatics, including the initial lacteals in the villi. The central lacteals were completely surrounded externally by the subepithelial blood capillary networks of the intestinal villi. Individual villi in the lower intestine contained only one central lacteal that drained through a thin lymphatic in the glandular layer into the submucosal lymphatic plexus. Villi in the upper small intestine were broader than those in the lower small intestine, and contained two to five lacteals. They anastomosed with each other at the villous base and formed a markedly expanded sinus. The cast submucosal lymphatics frequently showed constrictions strongly suggestive of valves. It was constantly observed that well-developed lymphatics in the submucosa ran in pairs and held an arteriole or artery between them. This close association of the lymphatics with arteries suggests that arterial vasomotion might provide an important hydrodynamic energy source for lymph formation and transport.

Animals↗
PubMed1985

Blood vascular bed of the rat pituitary intermediate lobe, with special reference to its development and portal drainage into the anterior lobe. A scanning electron microscope study of vascular casts.

Blood vascular beds of the rat pituitary intermediate lobes were reproduced by injection of low viscosity methacrylate media, and then observed with a scanning electron microscope. Although the intermediate lobes of newborn and pubescent rat were poorly vascularized, the adult rat intermediate lobe contained numerous capillaries forming a fairly independent network whose density, however, was not so great as in the anterior and posterior lobes. The vascular network of the intermediate lobe could be divided into two parts: a superficial plexus close to the anterior lobe, and a deep one close to the posterior lobe, though the two plexuses were continuous with each other. The superficial plexus consisted of anastomosing capillaries, and the deep one of non-anastomosing capillaries with a palisade-fashioned arrangement. The superficial plexus seemed crucially important for the blood supply of the intermediate lobe since it developed or thickened as the animals aged. The superficial plexus received its proper afferent vessels from the middle and posterior hypophyseal arteries and emitted its proper efferent vessels continuous with the sinusoidal capillaries of the anterior lobe. The capillaries of the deep plexus usually communicated with the arterial capillaries of the posterior lobe and possibly represented another afferent route to the superficial plexus. This paper, thus, strongly suggests a portal circulation from the intermediate lobe to the anterior lobe though its functional significance is unknown.

Aging↗
PubMed1984

Microvascular architecture of the pampiniform plexus-testicular artery system in the rat: a scanning electron microscope study of corrosion casts.

The vascular architecture of the rat pampiniform plexus was studied by scanning electron microscopy of vascular corrosion casts. The plexus consists of a thick bundle of many anastomosing veins that entirely and closely surround the convoluted segments of the testicular artery. This specially developed close contact of the pampiniform plexus with the testicular artery may allow heat exchange between the plexus and the artery to maintain the cooled condition of the testis. The epididymal arteries are also closely surrounded by the networks of the epididymal veins. It is likely that heat exchange may operate even between these epididymal vessels. The ductus deferens is provided with no vascular channels for such heat exchange. A loose or coarse capillary network is always observed between the testicular artery and the pampiniform plexus. This network is supplied by the epididymal arteries and drains into the pampiniform plexus.

Animals↗
PubMed1984

A monomeric methyl and hydroxypropyl methacrylate injection medium and its utility in casting blood capillaries and liver bile canaliculi for scanning electron microscopy.

A mixture of 50-60% monomeric methyl methacrylate and 40-50% monomeric 2-hydroxypropyl methacrylate was supplemented with 1.5% benzoyl peroxide (catalyst) and 1.5% N,N-dimethylaniline (accelerator) and injected into glutaraldehyde-perfusion fixed rat hypophyseal and other endocrine organ blood vessels and biliary tracts. This injection medium rapidly polymerized at room temperature and did not require partial polymerization prior to injection. Good casts of blood vessels, including the hypophyseal capillaries, were obtained for scanning electron microscopy. The monomeric methacrylate medium possesses a great advantage over previous ones, as its fluidity enables the casting of very fine vessels such as bile canaliculi. In the case of non-fixed tissues, the monomeric methacrylate medium should be injected carefully, as it is toxic and destructive to the vessels.

Acrylates↗
PubMed1984

The microvascular architecture of the rabbit stomach corpus in vascular corrosion casts.

The blood vessels of the rabbit gastric mucosa were reproduced with a methacrylate casting medium and observed in a scanning electron microscope. The submucosal arteries gave off short and long arterioles. The short arterioles connected at the base of the fundic glands with the capillary network surrounding the glands. The long arterioles ascended along the glands and supplied the capillary network beneath the surface epithelium. This capillary network was denser than the capillary network around the glands. In the glandular neck region, there were many capillary connections between the surface epithelial and glandular capillary systems, but both of these capillary networks drained into common venules which descended along the glands and emptied into the submucosal veins. The isolated arterial supply of the surface mucous cell layer may assure enough blood circulation in this layer for the surface mucous cells to produce a sufficient amount of HCl-resistant mucous or to protect the epithelium against the acid in the gastric lumen.

Animals↗
PubMed1983

The microvasculature of rat salivary glands. A scanning electron microscopic study.

The blood vessels together with the parenchymal components of rat salivary glands were studied by scanning electron microscopy (SEM) after removal of stromal connective tissue by acid hydrolysis plus enzymatic digestion. The three-dimensional vascular architecture was also studied by SEM of vascular corrosion cats. Each cluster of 4-5 polymorphous acini is connected with the convoluted duct via an intercalated duct. The convoluted duct usually has a sigmoid course and drains to the intralobular striated duct (about 20 microns in diameter); this has a rather straight course before connecting with the interlobular excretory duct. Myoepithelial cells with radiating processes were observed on the stromal surface of the secretory acini. Pericytes with longitudinal and circular processes were also observed surrounding the stromal surface of capillaries. The acini and convoluted ducts are surrounded by plexuses of capillaries derived from terminal arterioles which run along the intralobular duct system. The sinusoidal capillary plexus enveloping the striated duct receives blood from capillaries surrounding the acini and convoluted ducts through portal venules. The interlobular excretory ducts are richly supplied by a subepithelial network of capillaries which receive blood directly from the interlobular artery and drain into the interlobular vein. Thus, the excretory duct circulation is separated from the intralobular circulation. No arterio-venous anastomoses were observed in the gland. However, veno-venous and arterio-arterial anastomoses were often seen along the excretory duct; such anastomoses may participate in controlling the direction of blood flow through the vascular plexus around the excretory duct. The well-developed subepithelial plexus of capillaries observed around this duct is appropriate for its known absorptive/secretory functions. The capillary network around the acini is densest in the parotid gland and sparsest in the sublingual gland. The subepithelial capillary network of the excretory ducts of the submaxillary gland is denser than those of the other two glands which had similar densities.

Animals↗
PubMed1983

Microvasculature as studied by the microvascular corrosion casting/scanning electron microscope method. I. Endocrine and digestive system.

This paper reviews firstly the microvascular corrosion casting/scanning electron microscope method and secondly the microvascular organization of endocrine and digestive system as revealed by this technique. Detailed descriptions of the microvascular arrangement of the hypophysis, pineal body, thyroid gland, pancreas, adrenal gland, salivary gland, liver, stomach and small intestine are given. Various hypotheses are also proposed regarding the physiological significance of the microcirculatory patterns observed.

Adrenal Glands↗
PubMed1983

Conductive staining of biological specimens for scanning electron microscopy with special reference to ligand-mediated osmium impregnation.

Biological specimens for scanning electron microscopy are made electron-conductive and non-charging by intense osmication with tannic acid, thiocarbohydrazide, hydrazine hydrate or other bifunctional ligands (or mordants). Such osmication also minimizes tissue shrinkage during dehydration and drying, reduces tissue damage during metal coating and scanning observations, and circumvents the use of a thick metal coating which hinders high resolution. Intense osmication when repeated eliminates the need for a metal coating and produces a well-contrasted scanning image with good resolution. Moreover, such osmication reduces tissue damage during ion implanting, enhances the depth of imaging, allows x-ray microanalysis without coated metals, and permits resin-embedded observations, as well as continuous or repeated microdissections in the scanning electron microscope without charging. Intense osmication forms a surface coat or thickens the cell membrane. This surface coat consists of electron dense deposits of 4-20 nm thickness. The hydrazine hydrate-osmium method can be used in the vapor phase. The vapor phase application has the advantage of staining even plastic samples for non-metal-coated scanning electron microscopy.

Animals↗
PubMed1982

Effect of prostacyclin infusion on active and inactive renin release in the isolated perfused kidney.

The effect of prostacyclin infusion into the renal artery of the isolated perfused hog kidney on the release of active and inactive renin was investigated. Infusion of prostacyclin at a rate of 0.1 microgram/min resulted in a significant increase (p less than 0.01) in active renin and a significant fall (p less than 0.01) in inactive renin. Prostacyclin also increased urinary kallikrein excretion (p less than 0.05). The results indicate that the kidney secretes not only active renin but also inactive renin, and suggest that prostacyclin stimulates the conversion of inactive renin to the active form through the activation of the renal kallikrein system.

Animals↗
PubMed1982

Double staining by vaporized osmium tetroxide-hydrazine hydrate of biological specimens for non-coated scanning electron microscopy.

Sufficient electron conductivity was obtained in biological specimens following double staining with vaporized osmium tetroxide and hydrazine hydrate for non-gold coated scanning electron microscopic observations. No charging was noted at 25 kV acceleration voltage in rat kidney, liver or other specimens. The foot processes of the glomerular podocytes and micropores of the glomerular endothelium as well as the intracellular endoplasmic reticulum of liver cells were particularly well visualized without the addition of evaporated metal. Repeating this vapor phase osmication method produced even higher contrast at high magnifications compared to the single vaporized osmication method.

Animals↗
PubMed1981

Mounting of biological microsamples on protein coats for TaOTO non-coated scanning electron microscopy.

Gelatin-coated glass cover slips were immersed in a mixture of glutaraldehyde and tannic acid, and rinsed in bovine or human serum. The gelatin-coated cover slips were first placed in a human blood cell suspension, and subsequently placed in a solution of glutaraldehyde or osmium tetroxide. This preliminary mounting of the blood cells eliminated troublesome centrifugations in the tannin-osmium-thiocarbohydrazide-osmium (TaOTO) impregnation. The blood cells seldom detached from the cover slips even when the specimens were dehydrated with ethanol and critical point dried with liquid carbon dioxide. Both the mounting media as well as the mounted cells were intensely stained by the TaOTO method, and exhibited no charging in the scanning electron microscope even at acceleration voltages of 25 kV. The scanning images of the white blood cells with their microvilli were clearly visible with sharp contrast.

Blood Cells↗
PubMed1981

[Follow-up study of the giant aneurysm by CT scan after unilateal carotid ligation (author's transl)].

We report a rare case of giant aneurysm of the anterior communicating artery, which was followed up by CT scan after unilateral carotid ligation. A 50-year-old female visited our clinic complaining of headache and visual disturbance. Neurological examination revealed bitemporal hemianopsia and loss of visual acuity. A giant anterior communicating artery aneurysm was found on right carotid angiograms. After ligation of the right common carotid artery, the aneurysm was reduced in size. Three weeks later, however, it ruptured and the patient died two months later. Autopsy showed the ruptured dome of the aneurysm. The wall of the sac lacked elastic fibers. It was considered that after carotid ligation the wall of the dome was pressed directly by the remaining blood flow, and the aneurysmal rupture was caused. We should give care to the aneurysm after carotid ligation.

Carotid Arteries↗