A scanning electron microscopy morphometric study of the rabbit peritoneal surface

Rabbit peritoneum was studied by SEM to obtain information and statistically meaningful morphometric data of different sites of visceral and parietal peritoneum and to verify the existence of "stomata." Samples were fixed by intraperitoneal infusion of glutaraldehyde, and were photographed by SEM under standard conditions. Morphometric data were obtained by Kontron MOP Videoplan. Variable cell surface patterns were present even within limited areas; however, "stomata" were not observed. The heterogeneity of data obtained can be related to the dynamism of mesothelial cell activity and to the different motilities of the underlying organs.     

Scanning electron microscopy of human lumbar vertebral trabecular bone surfaces

Summary Trabecular bone from fourth lumbar vertebral bodies of 30 autopsy subjects (18 male and 12 females, 30–91 years of age) was investigated using surface mode scanning electron microscopy. In the younger individuals, proper coupling of formation and resorption appeared to have maintained both the bone mass and the shape and structural integrity of the trabecular elements. In elderly individuals, including osteoporotics, irregularities and uncoupling of these activities brought about a loss of bone and a disruption of trabecular structure. Distinct resorption patterns (lateral and vertical) are responsible for trabecular thinning and removal of structural elements. Irregularities in the formative process in old age may account for the compensatory thickening and changes in shape and texture of trabecular elements. The mechanisms involved in the occurrence of microfractures and the fate of disconnected elements were also identified. An increased proportion of arrested mineralizing fronts is found in older individuals and in frank osteoporotics. Resorption may occur through osteoid and arrested mineralizing fronts, as well as through resting, fully mineralized surfaces.     

A scanning electron microscopy study of the interface between ceramics and bone

By use of scanning electron microscopy (SEM), together with energy dispersive chemical analysis, a study has been made of the comparison of an in vitro method of assessing interface reactions between bone and ceramic implants with the naturally occurring changes seen in the rat ear model. Interface reactions between bone and two ceramic materials were examined following 4 wk in culture and 4 wk implantation. In both cases a gradual chemical change occurred at the calcium silicate surface during the fibrous growth onto the ceramic material. Gradual mineralization of the connective fibres was found at the interface of the calcium silicate material, whereas, in the case of alumina ceramic a connective fibrous bond had formed with no associated chemical change at the ceramic surface.     

The surface anatomy of the human aortic valve as revealed by scanning electron microscopy

Summary The anatomy of the human aortic valve was studied by SEM in 36 subjects without cardiac pathology who had died of various accidental causes. Villous and lamellar tissue excrescences were observed at the node of Arantius and at the limit between the lunules and the load-bearing portion of the leaflets. The morphology of these structures suggests that they represent areas in which valve tissue becomes detached into the bloodstream. Fenestrations were present in the lunules of 14 specimens, with a higher incidence in specimens from subjects who were middle-aged or older. Our observations suggest that fenestrations appear initially as small perforations which then coalesce to form larger apertures.Two main types of endothelial cells, elongated and polygonal were detected on the endothelial surface of the leaflets. Both types of cells display a constant mode of arrangement on the different segments of the leaflets (lunules, node of Arantius and load-bearing portion of the leaflet). The possible relationships between endothelial cell morphology and the pattern of mechanical stress to which the leaflets are subjected is discussed.     

The three-dimensional microstructure of the trabecular bone in the mandible

This study investigated the three dimensional (3D) trabecular microstructure of the alveolar and basal bone in the mandible using micro-CT and compared the morphometric values of the different sites. Ten specimens were prepared and scanned using a micro-CT system. Both the alveolar and basal trabecular bone of the premolar region in the mandible were measured for the structural analysis. Cross-sectional 1024×1024 pixel images were created. From the two-dimensional (2D) images produced, 3D structural images were reconstructed. After scanning the specimen, the volumes of interest (VOI) of the alveolar and basal bone regions were selected from the 3D reconstruction images, and the structural parameters such as bone volume fraction, bone surface density, trabecular thickness, trabecular separation, trabecular number and structural model index were analyzed. The trabecular structure showed a marked variation within the sites of the specimen, especially in the basal trabecular bone inferior to the mandibular canal. In both the alveolar and basal bone regions, a mixture of both plate-like and rod-like structures was observed. The alveolar region showed a more compact, plate-type trabecular structure than the basal regions. In parametric comparison with the basal bone, the alveolar bone generally had a higher bone volume fraction, bone trabecular thickness and trabecular number, and lower bone surface density, trabecular separation and structural model index. The alveolar bone consisted of a compact bone structure with a large amount of thick plate-type trabecular bone, which was effectively resistant to the masticatory forces. As the measurements were made closer to the basal bone, a loose structure was observed with lower bone volume and fewer, thin, rod-like trabeculae.     

Mesoscopy and scanning electron microscopy of the trabecular projections in the superior sagittal sinus

The trabecular projections of the human superior sagittal sinus were classified into types and subtypes according to spatial arrangement and shape. The horizontal and vertical projections direct laminar blood flow, while the conic type, which is avalvular, protects the openings of the superior cerebral veins in the superior sagittal sinus.     

Elastin and collagen remodeling in emphysema. A scanning electron microscopy study.

The relationship between elastin degradation and emphysema is well known. Recent evidence suggests that a complex process of pulmonary remodeling occurs within the emphysematous lung. The aim of this study was to assess the extent of extracellular matrix remodeling in emphysema by ultrastructural examination of elastin and collagen templates in an animal model of emphysema and in human emphysematous lungs. Emphysema was induced in rats by the intratracheal administration of porcine pancreatic elastase. Human lung samples were obtained at surgical resection for lung carcinoma. Emphysema was confirmed morphometrically and quantitated using the mean linear intercept. Matching sections were treated with sodium hydroxide and formic acid to expose collagen and elastin templates, respectively. Scanning electron microscopy with stereo-pair imaging allowed three-dimensional visualization of the exposed templates. In emphysematous lungs from both sources, sheets of elastin were disrupted and perforated with multiple fenestrations. In elastase-induced emphysema, this disintegration was accompanied by a marked increase in thickness of collagen fibrils, which contrasted with the fine fibrillar network of control lungs. Similarly, a pattern of thickened fibrils and disorganized deposition of collagen was observed in human lungs. In conclusion, these findings support the novel concept of increased collagen deposition and aberrant collagen remodeling in the pathogenesis of emphysema.     

Pneumocystis carinii in vitro: A study by scanning electron microscopy.

Pneumocystis carinii is a parasitic microorganism which induces an often fatal pneumonitis in a variety of compromised patients (e.g., premature infants, those with congenital immune deficiency disorders, those therapeutically immune suppressed, etc.). Organisms derived from murine sources were cultivated in vitro on monolayers of primary embryonic chick epithelial lung cells. The infected cultures were then examined by scanning electron microscopy. An examination of the surface ultrastructure revealed pleomorphic organisms which were not only attached to host cells with anchoring fibers but also connected to other parasites via fine fibrils. Another type of fine fibril was observed which may play a role in the organism's nutrition.     

A scanning electron microscopy study of human osteoblast morphology on five orthopedic metals

Despite the long-standing use of metals as orthopedic implants there still are unsolved problems with these materials and open questions about their behavior in a biological environment. Cell-culture studies provide a useful tool for investigations. In addition to the determination of biochemical or molecular biological parameters, the morphology of adhering cells reflects their interaction with the substrata. This article describes an investigation of the morphology of human osteoblasts on stainless steel, cobalt chromium alloy, commercially pure titanium, Ti-6Al-4V, and Ti-6Al-7Nb with surface designs similar to those used as clinical implants. A cell culture plastic surface was used as a control material. The materials were examined by scanning electron microscopy at different points of time. The cells spread, proliferated, and formed nodules on all test substrates in a time-dependent manner, without signs of a disturbing influence from any of the materials. On the smooth surfaces the cells showed a flattened fibroblast-like morphology and only slight differences could be detected. Therefore, the cellular morphology seems not to be markedly affected by the different chemical material compositions. In contrast, the titanium alloy with a rough, sandblasted surface induced a three-dimensional growth. This three-dimensional cellular network could be the basis for the known earlier differentiation of osteoblasts on rough surfaces in vitro and a better osseointegration in vivo.     

Investigation of human chromosome polymorphisms by scanning electron microscopy.

Human chromosome polymorphisms were investigated by scanning electron microscopy (SEM). Centromeric heterochromatin was of a constricted morphology. The extent of the C banded region was demarcated by a prominent circumferential groove in G banded chromosomes. Circumferential grooves were observed within the heterochromatin of chromosome 9, and the number of grooves present reflected the size of the region. Three dimensional viewing of satellites and short arms of acrocentric chromosomes, from different angles in the SEM, provided the opportunity for accurate assessment of the size of satellites to be made. Also, small morphological variations were defined in the SEM when definition was uncertain in the light microscope (LM).     

The three-dimensional microvascular arrangement around rat dorsal hairs as revealed by scanning electron microscopy

The three-dimensional microvascular arrangement around the dorsal hairs in vascular corrosion casts of adult Wistar rats was studied by scanning electron microscopy. Each anagen dorsal hair was surrounded by a 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 dorsal hair was denser at its lower part, and became more sparse at its upper part. Transmission electron microscopy showed that the capillaries around the hair bulb possessed fenestrations. Our findings indicate that the microvascular arrangement around the anagen dorsal hair is so organized as to supply the hair bulb, which is the most important area for hair growth, with abundant blood. This study was presented at the 24th Annual Meeting of the Clinical Electron Microscopy Society of Japan, Okayama, September 17–19, 1992.     

The three-dimensional microvascular arrangement around rat vibrissa hairs as revealed by scanning electron microscopy

The three-dimensional microvascular arrangement around the vibrissa hairs in vascular corrosion casts of adult Wistar rats was studied by scanning electron microscopy. Each hairshaft was surrounded by the sinus, which consisted of the superficial ring sinus and the deeper cavernous sinus. Many trabeculae existed in the cavernous sinus but not in the ring sinus. The hairshaft within the cavernous sinus was surrounded by a basket-like capillary network which was denser at its lower part. On the inside of the ring sinus, only a few arterioles ascended along the hairshaft. Our results indicate that the lower part of the vibrissa hair, which is the most important area for hair growth, is supplied with a more abundant blood supply and is protected from external forces by the cavernous sinus with its many trabeculae. This study was presented at the 25th Annual Meeting of the Clinical Electron Microscopy Society of Japan, Matsumoto, September 28–30, 1993.     

A scanning transmission electron microscopy study of two dental amalgams

Two fully aged amalgam alloys were examined using a scanning transmission electron microscope both in the transmission and scanning mode. The dispersed type amalgam containing a distribution of silver-copper spheres in addition to the Ag₃Sn powder showed a markedly reduced γ₁ grain size compared to a conventional Ag₃Sn type amalgam.

It is suggested that the increased compressive creep strength of the dispersed type material is a direct result of the reduced γ₁ grain size and not due to a dispersion hardening effect from the cores of the remaining Ag-Cu spheres. Similarly, the formation of complex Cu-Sn intermediate phases at the Ag-Cu sphere surfaces are unlikely to lead to a dispersion strengthening effect.

It is postulated that the reduced grain size in high copper amalgams is a consequence of the enhanced nucleating effect of a copper based phase on γ₁     

Transmission and scanning electron microscopy study on Burkitt-like leukemia.

A young patient had Burkitt-like leukemia. The diagnosis was based on the presence of numerous vacuoles observed with the light microscope and confirmed by the finding of large lipid droplets and abundant ribosomes in the cytoplasm of the leukemic cells, seen with the transmission electron microscope. Scanning electron microscope examination of the leukemic cells showed the presence of a smaller number of microvilli and ruffles on the cell surface, which distinguished these cells from the blasts of other types of leukemia.     

The 3D structure of the human urinary bladder mucosa: a scanning electron microscopy study

We performed a scanning electron microscopy study on the human urinary bladder tunica mucosa. Specimens from bladder biopsies were treated with OsO4 maceration and 1N NaOH maceration methods prior to SEM observation to disclose the three-dimensional organization of the lamina propria, basal lamina and urothelium. The lamina propria housed a well developed capillary plexus just below the basal lamina; the urothelium presented a typical three-layered organization with basal, intermediate and superficial cells. The intermediate cells appeared essentially similar to basal cells in their external features and stretched from the basal lamina up to the superficial layer. The most superficial cells appeared consistently flattened and interconnected by extensive junctional complexes. They showed a peculiar specialization, their apical plasmalemma being thickened with distinctive, stiff plaques, in contrast with the underlying globular or spindle-shaped cells whose plasmalemma was only covered by short microvillosities.     

Endothelial cell helix in small arterioles of human ureters. A study by scanning electron microscopy (SEM).

Microvessel corrosion casts of human ureters were prepared. Portions of casts were longitudinally cut by use of a pulsed Eximer laser beam in order to get insight into microvessel branches studied in SEM. Larger arterioles (greater than 30 microns in diameter) showed oval imprints of endothelial cell nuclei along the vessel axis. Imprints were found in furrows parallel to resin ridges. Smaller arterioles (less than microns in diameter) displayed imprints of nuclei aligned in a helix around the vessel axis. With regard to capillaries, one nucleus imprint was spaced far apart from the other. Venules demonstrated a reticular network of thick, attenuated resin ridges and of small meshes which consisted of round or oval nucleus imprints. It is concluded that smaller arterioles form an endothelial cells helix.