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PubMed1981

The effect of cleaning soft contact lenses. A scanning electron microscopic study.

Scanning electron microscopy was used to investigate the effectiveness of surfactant and enzyme cleaners in removing coatings from soft contact lenses. We examined ten continuously worn lenses and 15 lenses worn and cleaned regularly for at six months. About 30% of the surface of continuously worn lenses cleaned with surfactant or enzyme was uncoated; smooth, matted coating covered the remainder. Continuously worn lenses cleaned with the combination surfactant and enzyme cleaner had similar deposits covering 50% of the surface. Lenses worn and cleaned regularly had more deposits after cleaning with surfactant or enzyme cleaner than after cleaning with combination cleaner. Approximately 25% of the surface of lenses cleaned with the combination was coated with deposits. The deposits on both types of lenses were about 30% less thick after use of the combination cleaner than with either single cleaner. The coating on worn contact lenses is not completely removed by any method we tested.

Contact Lenses, Hydrophilic↗
PubMed1998

Perivascular structures in corrosion casts of the human central nervous system: a confocal laser and scanning electron microscope study.

Scanning electron microscopy (SEM) of microvascular corrosion casts revealed perivascular structures that resembled smooth muscle and pericyte cells. Although these structures have been studied in widely different experimental contexts, their origin, function, and distribution pattern in different tissues are not understood. Microvascular corrosion casts from 15 fresh human brains and 20 lumbar spinal cords were studied by SEM. In five cerebral hemispheres a fluorescent resin was injected in order to study the vascular bed by confocal laser scanning microscopy (CLSM). Microvascular casts showed two perivascular structures on their surfaces: plastic strips, which formed a muff around arteriolar vessels, and pericyte-like structures that were present around the capillary network. Their morphological characteristics and distribution were similar to those of smooth muscle cells and pericytes, respectively. The SEM study showed that these structures were not tightly joined to the cast surface, but were connected to the vascular cast by narrow plastic connections. The CLSM showed that the resin invaded the subendothelial space, thus giving rise to these structures. Perivascular structures associated with arteriolar and capillary vessels appear to represent smooth muscle cells and pericytes. They are formed by the passage of the resin to the subendothelial space, probably through weak endothelial cell junctions. The effusion of resin into the subendothelial space may represent evidence for the structural basis of myocyte and pericyte cell control. Chemical communication by substances released locally or transported to these cells through these junctions may regulate their functions, allowing them to regulate blood flow.

Adult↗
PubMedDate not supplied

Conditions for imaging emulsions in the environmental scanning electron microscope.

Environmental scanning electron microscopy (ESEM) is a technique capable of imaging volatile and/or insulating samples in their natural state, without prior specimen preparation. It is thus a powerful potential tool for the study of the structure and dynamics of emulsions and other complex liquid systems, at a resolution greater than that obtainable by conventional optical microscopy. We present images of a variety of liquid systems containing micron-scale and smaller features. The morphology of these systems may be clearly discerned. The contrast observed between the liquid phases was consistent with the model proposed by Stokes et al. (1998). The limits of resolution were determined by sample motion and by beam damage effects; under optimum conditions, resolution of a few tens of nanometers was obtained. This compares favourably with conventional and confocal optical microscopy. In some samples, thin films (solid or liquid) could be observed at the liquid/gas interface. Some of these films were so thin that they did not completely obscure the underlying structure of the bulk sample.

Journal Article↗
PubMed1983

Age-related changes in the cutaneous basal lamina: scanning electron microscopic study.

Scanning electron microscopy of human epidermal-dermal basal lamina demonstrated striking age-related changes. The basal lamina from abdominal skin was exposed in specimens from 26 humans by separation of epidermis and dermis after treatment with sodium bromide solutions. Transmission electron micrographs demonstrated the split to be in the lamina lucida. Scanning electron microscopy of mature epidermal-dermal junction and basal lamina showed distinct dermal valleys; tall, dome-shaped dermal papillae; and basal lamina arranged in prominent corrugations that tended to be oriented vertically on papillae and irregularly on interpapillary zones. Skin from subjects in their 7th through 10th decades demonstrated progressive loss of dermal valleys, flattening and widening of dermal papillae, and loss of basal lamina corrugations.

Adolescent↗
PubMed1986

Cytology of human intraocular lenses. A scanning electron microscopic study.

Scanning electron microscopy of 9 intraocular lenses, removed from patients mainly because of corneal problems, revealed the presence of different types of adhering elements. Independent of clinically significant symptoms of infection, macrophages and/or epitheloid cells and/or granulocytes were observed. On their anterior surface, 3 lenses showed flat cells or cellular remains which are supposed to represent corneal epithelial cells. Membrane fragments were found on 3 other lenses. Most of the polymethylmethacrylate optics of the lenses showed some deformation and/or cracking and to evaluate them some additional studies with new intraocular lenses were performed. High pressure during the preparation procedure for scanning electron microscopy was found to be the cause.

Cell Adhesion↗
PubMed1975

The normal surface of conjunctiva epithelium. A scanning electron microscopic study.

Scanning electron microscopy (SEM) of the cellular surface of the rabbit conjunctiva show the monotonous appearance of fine, finger-like cytoplasmic protrusions (microvilli) covering the polygonal cells. Many of these surface cells contained a variety of intracytoplasmic vesicles, unroofed vesicles, and full-thickness holes of different sizes. These surface changes were interpreted as occuring in a sequential pattern leading to cell destruction and exfoliation. Interspersed among these light and dark polygonal cells were goblet cells representing various stages in their maturation. Specialized filopodia were found between epithelial cells only in the area just proximal to the tarsi. Duct openings of many glands were shown to enter onto the conjunctival surface. The relation of these finding to the tear film is discussed.

Animals↗
PubMed1976

The effects of ophthalmic drugs, vehicles, and preservatives on corneal epithelium: a scanning electron microscope study.

Scanning electron microscopy was found to be of considerable use in evaluating the effects of various commonly used drugs, vehicles, and preservatives on the corneal surface. Of the preparations tested 0.3 per cent gentamicin caused many central cellular microvilli to stand up prominently. Moderate losses of peripheral microvilli, with mild superficial cellular desquamation was noted with 0.25 per cent phospholine iodide, 2 per cent pilocarpine, 2 per cent fluorescein, and Fluor-I-Strip. The top layer of epithelial cells desquamated with 4 per cent cocaine or neopolycin treatment. The top two layers of cells were lost when 0.01 per cent benzalkonium chloride was instilled. When cell death occurred severe membrane disruption was accompanied by loss of microvilli and rupture of intercellular tight junctions. These studies show that the cytotoxicity of topical ocular preparations can be tested in an in vivo model and evaluated by scanning electron microscopy.

Anesthetics, Local↗
PubMed1992

Migration of polymorphonuclear leukocytes through human amnion membrane--a scanning electron microscopic study.

Scanning electron microscopy has been used to examine the changes in the basement membrane structure induced by polymorphonuclear leukocytes during leukodiapedesis. A diapedesis model based on a Boyden chamber fitted with a human amnion membrane simulated inflammatory processes during which leukocytes are stimulated to leave blood vessels and to penetrate basement membranes. In the Boyden chamber, a chemotactic gradient was developed from a solution of 10(-7) M formyl-methionyl-leucyl-phenylalanine, which induced the cells to migrate through the membrane. Our observations suggest that leukocytes, like tumor cells, emigrate in a three-step process. In the first instance, they adhere to the basement membrane. A local partial proteolysis follows, which is caused by secreted metalloproteinases, especially by gelatinase. The partial dissolution of the matrix facilitates cell penetration. Active locomotion and squeezing through the residual membrane matrix allows the cells to penetrate without complete local membrane destruction. The last step involves migration of the cells through the connective tissue barrier to the site of infection. The type I collagen fibres which form this loose stroma tissue are no obstacle and can be pushed aside without proteolytic degradation.

Amnion↗
PubMed1981

[Erythrocyte interaction during aggregation according to scanning electron microscope findings].

Scanning electron microscopy was used to study red cell aggregation caused by intravascular injection of dextran (m. w. 500 000). Two types of aggregates were revealed. Type 1 was represented by aggregates of red cells with no substantial change in the form while type 2 by aggregates with the wrinkling of the surface of red cells and enlarged area of red cell surface contacts. Both types are prone to disaggregation after injection of rheopolyglucin.

Animals↗
PubMed1979

Surface configuration of mesothelial cells in effusions. A comparative light microscopic and scanning electron microscopic study.

Surface configuration of mesothelial cells identified by light microscopy (LM) has been studied by scanning electron microscopy (SEM). It has been shown that mesothelial cells may have a variable SEM appearance. The surfaces of a small proportion of mesothelial cells are covered by regular microvilli (MV) and show openings of the pinocytotic vesicles. The surfaces of the majority of these cells are covered by vesicles or blebs. An intermediate population of mesothelial cells, i.e., cells displaying side-by-side blebs and MV, has also been observed. The latter cells no longer display pinocytotic vesicles. Occasional mesothelial cells have smooth surfaces. It has been shown by LM and transmission electron microscopy that cells with blebs are viable and capable of mitotic activity. It is concluded that mesothelial cells, detached from their epithelial setting, lose microvilli and pinocytotic vesicles and acquire surface blebs. The possible relationship between mesothelial cells and macrophages based on surface features has been discussed.

Animals↗
PubMed1979

Crohn's disease: a scanning electron microscopic study.

A scanning electron microscopic study of Crohn's disease was done using surgically resected specimens. Grossly normal resection margins as well as nonulcerated portions from diseased areas were selected for study. Scanning electron microscopic findings in Crohn's disease included changes in villous size and shape, villous fusion and epithelial bridge formation, goblet cell hypertrophy and hyperplasia, and increased secretion of mucus. These changes were marked in involved areas, and many were also present in six of seven margins of resection available for study in the ileal group. The abnormalities found in grossly normal margins of resection suggest a more widespread involvement than can be appreciated by gross and light microscopic examination of the specimen. Formation of the increased coat of mucus observed may be stimulated by a number of agents and could contribute to an enhanced barrier function in areas of early involvement in Crohn's disease, thereby decreasing the uptake of toxic or antigenic macromolecules. A decrease in bacterial superinfections would also be facilitated. Later lesions, with severe villous changes and hypersecretion of mucus, may favor the uptake of toxic and antigenic macromolecules as well as aid in the establishment of bacterial superinfections.

Adolescent↗
PubMed2000

Vascular proliferation and blood supply during distraction osteogenesis: a scanning electron microscopic observation.

This scanning electron microscopic study examined the spatial and temporal features of proliferating vessels of regenerating bone tissue and blood supply during distraction osteogenesis. A rat model of tibial lengthening was used with a protocol divided into a latency period of 7 days, a distraction period that lasted 14 days with a daily distraction rate of 0.5 mm in two steps, and a consolidation period of 21 days. Vascular casting was done on the hindlimbs before osteotomy and on postoperative days 7, 14, 21, 28, and 42. Scanning electron microscopic findings were correlated with radiological and histological observations. On days 7 and 14, the proliferation of periosteal vessels was pronounced and there was distinct subperiosteal bone formation on the osteotomized surfaces. On day 21, vascular branches from the medullary canal of the host bone formed a vascular network, which gave rise to multiple axial, straight vascular branches, running parallel to the direction of distraction, toward the interzone, in accordance with the progress of mineralization. On day 28, the periosteum provided vascularization to the peripheral side of the interzone whereas the center of the interzone was still relatively avascular. On day 42, the periosteal and medullary vascular channels were completely connected at the distraction site including the interzone, which was occupied by developing and mature bone trabeculae. These results suggest that vascular proliferation occurs actively during the latency and distraction periods and then gradually decreases over time. A close temporal and spatial relationship exists between formation of regenerated bone and vascular proliferation of the periosteum and medullary canal.

Animals↗
PubMedDate not supplied

Configuration of surfaces of human cancer cells obtained by fine needle aspiration biopsy: a comparative light microscopic and scanning electron microscopic study.

The surface configuration of human cancer cells removed from their natural setting by fine needle aspiration biopsies was studied by scanning electron microscopy. Cells from several carcinomas of the breast, malignant melanomas, oat cell carcinomas and a malignant lymphoma were the subject of this study. Only viable cells, identified by light microscopy prior to scanning, were selected for study. Contrary to prior observations on cancer cells in effusions, the surface configuration of human cancer cells obtained directly from tissues is variable and may depend significantly on the histologic patterns.

Breast Neoplasms↗
PubMed1986

The characteristic structural features of the blood vessels of the Lewis lung carcinoma (a light microscopic and scanning electron microscopic study).

Vascular corrosion casts of Lewis lung carcinomas (LLC) grown subcutaneously in C57BL/6-mice are correlated with histological sections and with tumor tissue prepared for scanning electron microscopy (SEM). By making low, medium and high pressure cast preparations we studied the influence of perfusion and injection pressure on the resulting cast sample. Three types of vascular proliferations are distinguishable in LLC: Small globular outgrowths on sinusoidal dilated tumor capillaries, caused by proliferation of their endothelial cells. New sprouts on surrounding host vessels, invading the small, still avascular implant. Superficially located, centrifugally running sprouts in peripheral regions of large tumors. They invade the surrounding host tissue. Vascular sprouts are of venous origin, have a fragmentary endothelium and are rather "leaky" if casted. High pressure preparations of large tumors reveal central avascular cavities surrounded by centripetally running, compressed and blind ending tumor vessels. Irrespective of the applied injection pressure, the casts always exhibit extravasal channels caused by degeneration of the endothelium of central tumor vessels. We show that SEM of vascular corrosion casts combined with histology not only demonstrates such contrary processes as the development of tumor blood vessels and the simultaneously occurring vascular degeneration, but also elucidates all other morphological characteristics of the tumor vascular system.

Animals↗
PubMed1986

The angioarchitecture of the Lewis lung carcinoma in laboratory mice (a light microscopic and scanning electron microscopic study).

53 Lewis lung carcinomas implanted subcutaneously into C57BL/6-mice were examined. The animals were killed at various stages of tumor growth (TG) and prepared for histology and for scanning electron microscopy (critical-point-dried tissue; vascular corrosion casts). Prior to casting animals were rinsed using different perfusion pressures. Casting was done by manual injection of the resin, whereby different influx-rates were applied resulting in low, medium and high pressure preparations. We discern 3 phases of tumor angiogenesis (TA) occurring during 4 stages of TG among which vasodilation establishes the first reaction of the host vascular system to a growing tumor implant. During this stage 1 of TG, tumor nidation, nearby sinusoidal dilated host capillaries form globular outgrowings (phase 1 of TA). Subsequently radially arranged sprouts, which preferentially arise from venous host vessels, grow into the centre of the implant (phase 2 of TA). Stage 2 of TG, early tumor growth, is characterized by necrosis of the central tumor tissue and the development of a central avascular cavity. Thus the tumor vascular system is organized like a hollow sphere with a central cavity and a peripheral vascular "envelope" with large vessels embracing the tumor and centrifugally growing vascular sprouts, which arise from the venous part of the vascular "envelope" and invade the surrounding host tissue (phase 3 of TA). During stage 3 of TG, late tumor growth, many vessels of the basket-like vascular "envelope" obliterate. In stage 4 of TG, prefinal phase, the peripheral vascular density decreases continuously. Thus vascular sprouting and proliferation of viable tumor cells is confined to basal regions of the tumor.

Arterioles↗
PubMed1984

Spatial arrangement of collagen fibrils in the articular cartilage of the mandibular condyle: a light microscopic and scanning electron microscopic study.

To determine the spatial arrangement of collagen fibrils in articular cartilage of the human mandibular condyle, ten healthy condyles obtained at necropsy were examined by light microscopy and scanning electron microscopy (SEM). Observations using light microscopy showed the existence of four different zones. The organization and alignment of the collagen fibrils were different in every zone and varied from layers to bundles of fibrils running parallel, obliquely, or radially to the articular surface. Observations using scanning electron microscopy revealed a thin, surface layer of disorganized small fibrils with a cotton-wool appearance and a well-organized architecture of collagen fibrils in every zone. It was concluded that the organization of collagen fibrils in articular cartilage shows a three-dimensional network with a special system in every zone.

Adult↗
PubMed1994

Light microscopic and scanning electron microscopic analyses of dental implants retrieved from humans.

This paper reports analyses obtained from 51 implant cases retrieved from humans and submitted to the AAIDRF-MCG Implant Retrieval Center. The undecalcified samples were embedded in PMMA and examined with scanning electron microscopy and with routine light or Nomarski microscopy. Cases included individual implants as well as 2 mandibles obtained at autopsy. Retrieved implants were sometimes shown to be encapsulated with connective tissue (CT), whereas other implants were apposed by bone, with only minimal CT association. In the latter cases, the implants were apposed by substantial amounts of viable bone. Nomarski microscopy disclosed the orientation and close apposition of the collagen bundles comprising the interfacial bone. In these cases where close bone apposition was observed to the implants, implant fracture was often the cause of failure. Periodontal lesions were reported around some implants showing a marked degree of inflammatory cell infiltrate (ICI). This study underscores the need for evaluation of failed human dental implants. Failure of implants placed longer than 10 years ago (perhaps loaded immediately) may be due to loss of bone support, CT encapsulation, and ICI (i.e., biological failure). Failure of more recently placed implants could also be due to this scenario, but failure was more often ascribed to biomaterial failure.

Alveolar Process↗