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At least 163 records · Page 9Linked to original sources
PubMed2003

Cellular lining of the sheep pineal recess studied by light-, transmission-, and scanning electron microscopy: morphologic indications for a direct secretion of melatonin from the pineal gland to the cerebrospinal fluid.

In the sheep, the pineal hormone melatonin displays nocturnal levels 20 times as high in the cerebrospinal fluid of the third ventricle as in the jugular blood. Moreover, in the pineal recess, the evagination of the third ventricle into the pineal stalk, the levels of melatonin in the cerebrospinal fluid are even higher than in the ventral part of the third ventricle. This finding suggests melatonin to be secreted directly from the pineal gland to the ventricular lumen of the pineal recess of this species. We have, therefore, studied the interface between the sheep pineal gland and the cerebrospinal fluid by light-, scanning-, and electron microscopy of the pineal recess, as well as the permeability of the interface by tracer injections into the third ventricle. First, we show that the classic ependymal lining of the third ventricle disappears in the superior part of the recess. In this area, bulging pinealocytes, displaying immunoreactivity for serotonin, directly appose the cerebrospinal fluid. This pineal-cerebrospinal fluid interface of the sheep is large compared with other species, especially rodent species. Intraventricular injections of horseradish peroxidase and fluorescein isothiocyanate showed that both these tracers could permeate from the pineal recess into the sheep pineal parenchyma. This permeation was due to the presence of gap and intermediate junctions connecting the pinealocytes apposing the ventricular lumen. Thus, our results show that endocrine cells in this specialized area of the ventricular system are in direct contact with the cerebrospinal fluid. This finding supports the physiological concept of a direct secretion of melatonin into the cerebrospinal fluid of the sheep pineal recess.

Animals↗
PubMed1979

[Comparative endoscopic, light microscopy and scanning electron microscopy studies of the gastric mucosa in patients with chronic uremia].

Ten patients suffering from chronic uremia were selected for comparison studies of gastric mucosa. With endoscopy erosive gastritis was seen in the corpus and antrum of five patients and in the fundus of two patients. Conventional microscopy (nine patients) revealed chronic gastritis I three times in the fundus and five times in the corpus. Gastritis II was localized once in the corpus and twice in the antrum. Gastritis III was present in the antrum of four patients. Under the scanning electron microscope lesions of gastric mucosa were present in all ten cases. Single cell necrosis (A), mucosal defects involving basal membrane (B), destruction of tunica propria (C), and muscularis mucosae with bleeding (D) were seen. Mucosal lesions A and B are early stages of gastric erosions. The most severe lesions were seen in the antrum mucosa with all three methods.

Chronic Disease↗
PubMedDate not supplied

Vascular interrelationships of near-term mink placenta: light microscopy combined with scanning electron microscopy of corrosion casts.

The microvasculature of the near-term zonary placenta of the mink has been studied using light microscopy and scanning electron microscopy of corrosion casts, prepared from maternal and fetal vessel systems, respectively. The zonary area, most important for placental exchange, includes a characteristic labyrinth. The labyrinth is composed of lobules oriented in a maternal-fetal direction. One maternal stem artery serves as the central axis of a lobule, and about six pairs of fetal stem arteries and stem veins of the chorionic primary villi mark the periphery of the lobule. Viewed from the fetal side of the labyrinth, this lobular structure presents a roughly hexagonal pattern, with the central maternal stem artery and radially oriented arteriolar branches giving the lobule the shape of a star. These arterioles frequently form bridges to neighboring lobular systems; however, the majority continue into the feto-maternally oriented three-dimensional network of maternal capillary sinusoids, which converge on the outlets of the maternal stem veins on the maternal side of the labyrinth. Maternal main crypts are delimited by the rays of the star-shaped lobules containing chorionic primary villi. The latter penetrate into maternal crypts from the fetal side, and are characterized by their axial arterial and venous stem vessels. Fetal secondary villi are arranged at different levels from these stem vessels. The secondary villi are characterized by arterioles and venules branching in pairs from the stem vessels and supply the tributary capillary complexes of terminal villi. The lobular structure of the placental labyrinth provides a three-dimensional framework of vessels where maternal capillary sinusoids and fetal capillaries meet in a one-way cross-current arrangement. The blood flow conditions and the peculiarities of the mink placenta interhemal membrane are compared to those of other carnivores and discussed with respect to the efficiency of the endotheliochorial placenta.

Animals↗
PubMed2004

A study of phase separation in peptide-loaded HPMC films using T(zero)-modulated temperature DSC, atomic force microscopy, and scanning electron microscopy.

Despite the widespread use of drug-loaded polymeric systems, there is still considerable uncertainty with regard to the nature of the distribution of the drug within the polymer matrix. The aim of this investigation was to develop thermal and microscopic techniques whereby the miscibility and spatial distribution of a model peptide, cyclosporin A (CyA), in hydroxypropyl methylcellulose (HPMC) films may be studied. The new technique of T(zero)-modulated temperature differential scanning calorimetry (T(zero) MTDSC), scanning electron microscopy (SEM), and pulse force mode atomic force microscopy (PFM-AFM) were used in conjunction to study films prepared using a solvent evaporation process, with a solvent extraction study performed to elucidate the nature of the observed phases. T(zero) MTDSC studies showed glass transitions for both the HPMC and CycA, with the T(g) for the HPMC and CycA seen for the mixed systems. SEM showed two spherical phases of differing electron density. PFM-AFM also showed spheres of differing adhesion that increased in size on addition of drug. Pixel intensity analysis indicated that the smaller spheres corresponded to CycA. Exposure of the films to dichloromethane, in which CycA is soluble but HPMC is not, resulted in the presence of voids that corresponded well to the spheres suggested to correspond to the drug. It was concluded that the system had undergone extensive or complete phase separation, and that the thermal and microscopic techniques outlined above are an effective means by which this issue may be studied.

Calorimetry, Differential Scanning↗
PubMed1988

The dento-gingival junction as seen with light microscopy and scanning electron microscopy.

The purpose of this paper is to review the anatomical relationship of the Dento-Gingival Junction as seen in the human dentition. The junction is described under light microscopy and then reviewed as seen in the SEM with the author's unpublished findings. The authors' material was derived from extracted human teeth with remaining marginal gingival tissue. The specimens were fixed with 2% glutaraldehyde in 0.15M sodium cacodylate buffer (pH 7.2) for 24 h. The specimens were then washed and freeze-fractured in Freon 113 using liquid nitrogen. Afterwards they were processed by freeze-drying or CPD methods, coated with gold, and placed in the scanning electron microscope (SEM) for viewing. These specimens demonstrated the presence of numerous Sharpey's fibers at the cemental surface. A large number of fibrils intermingled with the fibers to produce a dense mass of tissue. Junctional epithelium, with the adjacent homogeneous dental cuticle was demonstrated. Plaque deposits on the tooth surface extended to a cell-free zone. Morphological detail viewed with SEM and light microscopy are compared.

Freeze Fracturing↗
PubMed1996

Deformed spinal needle tips and associated dural perforations examined by scanning electron microscopy.

BACKGROUND: The tips of modern thin Quincke-type spinal needles may be easily damaged by bone contact during the puncture. The purpose of this study was to find out the frequency of tip deformation in routine clinical work and the appearance of the dural perforations made by such damaged needles. METHODS: Two hundred and ninety-five Quincke-type needles (22G-29G) used in routine spinal anaesthesia were inspected by light microscopy. Scanning electron micrographs were taken of some of the damaged tips and of experimental dural perforations made by these. RESULTS: Four per cent of the needle tips were clearly bent or hooked and 11% were slightly bent. When an introducer needle was used (19 cases), one needle was clearly bent and one slightly bent. A puncture with a bone contact was associated with clear tip damage in 7%; a puncture without bone contact resulted in an undamaged or slightly bent needle tip in 99% of the cases. The numbers of bent tips among the various sizes were: 22G-2/21, 25G-13/40, 27G-28/231, 29G-1/3. In scanning electron microscopy (SEM) images of four clearly bent needle tips the deviation of the tip was between 10 microns and 20 microns. In SEM of eleven dural perforations, the holes made by needles with clearly bent tips were almost closed and three of them exhibited an "open tin can" appearance. None of the dural perforations was badly torn. CONCLUSIONS: We verified that the tips of modern thin spinal needles are vulnerable to damage due to contact with bone. However, the holes made in dura by needles with bent tips do not appear to be excessively torn.

Adolescent↗
PubMedDate not supplied

Hot isostatic pressing-processed hydroxyapatite-coated titanium implants: light microscopic and scanning electron microscopy investigations.

Hot isostatic pressing (HIP) was used in a new procedure to produce hydroxyapatite (HA) coatings on a commercially pure titanium (cpTi) substrate for osseous implantation. Eighteen HIP-processed HA-coated implants were placed in the inferior border of the mandibles in 2 Labrador retriever dogs and left submerged for 3 months. As control specimens, 12 sandblasted cpTi implants were placed in the same mandibles and, to compare the bone reaction, 2 additional plasma-sprayed HA-coated implants (Integral) were placed. Tissue reactions at the bony interfaces of the implants were studied in ground sections with the implants in situ, using ordinary, fluorescent, and polarized light microscopy and scanning electron microscopy (SEM). The HIP-processed HA coatings displayed an increased density in light microscopy and SEM as compared to plasma-sprayed coatings. Direct bone-implant contact was found in all 3 types of surfaces. However, the production of new bone was far more abundant for the HA-coated implants than for sandblasted cpTi implants. The presence of bone-forming and bone-resorbing cells indicated active bone remodeling in the interface area at 3 months after implant placement. The present results support the view that epitaxial bone growth may occur from the HA-coated implant surface. It was concluded that the increased density of the present HIP-processed HA material does not reduce the bioactive properties of the coatings.

Animals↗
PubMedDate not supplied

[Isolation of erythroblastic islands. Study by optical and scanning electron microscopy (author's transl)].

1. A simple technique is described for isolation and estimation of number of erythroblastic islands (EBI) in rat bone marrow. The number of EBI decreases during hypertransfusion polycythemia, and increases during experimentally-induced hemolytic anemia. It has also been possible to maintain EBI in vitro, under culture conditions, for up to 36 hours. 2. Each EBI contains a central cell having the character of a macrophage-histiocyte which adheres to glass and spreads, while still retaining its connections with the erythroblasts. 3. In an EBI the erythroblasts are arranged in the form of concentric rings, with the outer cells being more mature than the inner. The outermost layer is frequently made up of reticulocytes even in the isolated island. The erythroblasts of a single ring appear to be at the same stage of maturation which suggests that they are derived from the same stem cell. 4. Using a coordinate reference system, studies of nuclear expulsion were made, by both optical microscopy and scanning electron microscopy.

Animals↗
PubMed1989

[Adhesive bonding system Wiron 88--Superbond--enamel, dentin. A study based on scanning electron microscopy and profile scanning].

The components of the bonding system Wiron 88--Superbond enamel, dentin were examined by scanning electron microscopy and profile scanning. Wiron 88 was corroded electrolytically using Korolyt A in the Eltrokor system. At 400 mA/cm2 and an exposure time of 7 minutes an optimal microretentive surface morphology was seen on SEM. Both shorter and longer exposure times did not produce the desired results. Profile scanning of corroded Wiron 88 to determine vertical and horizontal surface changes showed that surface roughness increased as a function of increasing exposure times. On SEM of the Superbond material placed in contact with corroded metal and enamel, retentive structures were found to spread, thus producing a micromechanical bond. Phosphoric acid treatment increased the diameter of the dentin canals so that penetration of Superbond in corroded dentin was better than in non-corroded dentin. These results and several years of clinical experiences in adhesive denture work establish the usefulness of combining electrolytically corroded Wiron 88 and Superbond.

Boron Compounds↗
PubMed1976

Light microscopy and scanning electron microscopy of Bathmostomum sangeri Cobbold, 1879, of elephants.

Bathmostomum sangeri is an intestinal parasite of the elephant. Males measured 12.15-14.25 mm in length; females measured 14.98-17.68 mm in length. Buccal capsule is well-developed and funnel-shaped. There is a raised and transverse fissure ridge around the oral margin. The internal wall of the buccal capsule is raised into a series of circular ridges or lamellae. Teeth or cutting plates could not be seen. Spicules are stout, wing-like structures. The telamon is pear-shaped, but a gibernaculum is not present. There are two pairs of papillae on the either side of the cloacal opening. The female tail is gradually tepering.

Ancylostomatoidea↗
PubMed1982

A comparative study on application of Nd-YAG laser radiation and electrocautery in canine gastric mucosa--magnified observations by dissecting microscopy and scanning electron microscopy, and histological examinations.

The mucosal change, the depth of injury and the healing process in the canine gastric wall after Nd-YAG laser (YAG) exposure and electrocautery were studied comparatively by magnified observations. The results were as follows: 1. Mucosal changes caused by the YAG laser beam were more localized within the exposure area than those by electric current. 2. The depth of tissue damage to the canine gastric wall by YAG laser exposure was easy to control when compared to that caused by electrocautery. 3. The healing time of the ulcer caused by the YAG laser was shorter than that caused by high frequency current. 4. In the present study on the mucosal changes due to laser exposure and electrocautery using endoscopy, dissecting microscopy and SEM, it was found that these examinations appear to be helpful as experimental procedures to clarify the detailed appearance of the mucosal surface. It was suggested that endoscopic application of the YAG laser to the gastrointestinal tract was safe and effective when compared with other procedures which have been applied endoscopically for diagnosis and treatment.

Animals↗