Scanning electron microscopy最新文献

Energy dispersive X-ray microanalysis in STEM (scanning transmission electron microscope) of freeze-dried cryosections from biological cells provides information on the subcellular element distribution in terms of dry weight concentration. The local dry weight content in the range of 5-50%, respectively the local water content within 50 to 95%, in different subcellular compartments can be determined by measuring the darkfield intensity by means of an annular detector in STEM. Calibration is done by measuring the darkfield intensity of similarly prepared cryosections from dextran-water-solutions in varying concentration. Thus, by combining the X-ray microanalytical data evaluated by the continuum method with the STEM darkfield values, wet weight concentrations of elements in subcellular compartments are obtained. The method was applied to fibroblast cells in suspension. The reliability of this method is compared with other techniques to measure mass and intracellular water by electron microscope methods.

The most frequently used resins for vascular corrosion casting Mercox Cl-2B, Mercox Cl-2B diluted with methylmethacrylate (MMA) monomer and various self prepared MMA and hydroxypropyl-methacrylate mixtures were tested with regard to their thermostability, shrinkage, viscosity and replication quality. It was found that tempering of the plastics improves their thermostability with the exception of Mercox Cl-2B and that shrinkage depends on the amount of monomers a resin contains. In detail; Mercox Cl-2B has the lowest shrinkage (8.018%) whereas a hydroxypropyl-methacrylate mixture possessed the highest (20.408%). But, on the other hand, viscosity decreases with the quantity of monomers. All resins tested were able to replicate structures of 260 nm height but the resins' quality of replication was found to be limited by the effects of shrinkage. Finally, a method to estimate the blood volume of organs and tissues with the help of vascular corrosion casts is given.

Acute duodenal ulcers are produced in mice as a remote ("abscopal") effect of irradiation to the lower mediastinum. Such lesions have been examined with scanning electron microscopy at 5, 8 and 28 days after irradiation with 18 Gy of X-rays. All the ulcers occur within the first 1 cm long segment of the duodenum which is endowed with Brunner's glands. The single lesions vary in size, shape and position. The damaged area often includes much of the duodenal circumference and is distinguished by conical or rudimentary villi, or even by the complete absence of villi. In contrast, around the periphery of the ulcer the villi are mostly vertical. Although the floor of these lesions appears to be covered with a continuous epithelial layer, during the first 4 weeks after irradiation the severity of the focal duodenal damage seems to increase gradually with time. The lesions have been compared with specimens from unirradiated mice and also with samples taken 3 days after partial thoracic irradiation when little damage is seen. The pattern of fully developed duodenal lesions differs greatly from that seen after direct irradiation where damage has not included localised ulceration in the samples of jejunum so far examined. The lesions induced by partial thoracic irradiation may be related to radiation injury to vascular or autonomic nerve targets in the lower mediastinum. Such injury could result in malfunction of the pyloric sphincter or could alter the secretion by Brunner's glands and thus lead to duodenal ulceration.

Established systems of long-term bone marrow culture (LTBMC) have contributed to our understanding of the interrelationships between the adherent stromal cells and the stem cells, committed progenitors and mature terminally differentiated cells. While cell-mediated or short range stromal interactions appear to be a major source of homeostatic control between the stromal microenvironment and the stem cells, positive and negative humoral influences or long-range mechanisms also regulate stem cell proliferation and differentiation. Adherent stromal conditioned medium generates factors which can trigger CFU-s into DNA synthesis within 18 hours or inhibit incorporation of tritiated thymidine into rapidly proliferating CFU-s. Other adherent stromal factors reduce proliferation and terminal erythroid differentiation of BFU-e. Stromal cells also produce a synergistic activity which stimulates formation of giant macrophage colonies in conjunction with CSF. Continued examination of these factors should lead to better understanding of the mechanisms involved in control of hematopoietic stem cell proliferation and differentiation.

Structural features of isolated, fractionated rat bone marrow endothelium were compared to those of marrow sinus endothelium in situ. Marrow endothelium was purified, first by density gradient sedimentation on Percoll and then subjected to centrifugal elutriation. Using antifactor VIII antibody staining (indirect immunofluorescent method), preparations of greater than 50% purified endothelium were obtained. By SEM, these cells were about 10 microns in size and showed smooth surface and numerous invaginations. These features were also observed in the in situ endothelium obtained by perfusion-fixation and freeze-cracking. In addition, in situ endothelium displayed numerous hemopoietic cells in migration through the endothelium. By TEM, isolated endothelium showed numerous vesiculations, giving the cell sponge-like appearance. This corresponded to numerous intracellular vesicles in sinus endothelium in situ, reflecting high magnitude of fluid and molecular transport across the endothelium. Weibel-Palade bodies were not seen in either form of the endothelium, despite the positive reaction for factor VIII-related antigen. This finding suggested that the cell, while possessing factor VIII-related antigen, does not store this protein.

The assessment of in vitro osteoclastic activity has, until recently, been dependent on the analysis of organ culture experiments. We have developed a single cell resorption assay so that the resorptive function of individual osteoclasts could be studied. This paper examines the biological variation in the sizes of resorption lacunae produced by bone cell cultures derived from neonate rats and rabbits, and prehatch or hatchling chicks. Cultures were run for 24h for all species; and in addition for 48h for rat, 9 or 12 hours for rabbit and 3-7 hours for chick. The numbers of the nuclei of osteoclasts seeded on to plastic were counted for all three species. SEM stereophotogrammetry was used to measure areas, volumes, and maximum and average depths of the lacunae using specially designed instruments and software. Rat osteoclasts were smallest, and more chick osteoclasts were very large. There was a species difference in the onset of resorption and the sizes of pits produced, the chick osteoclasts being more vigorous resorbers than the rabbit ones, and the rat least so. For a given plan area, chick lacunae were deeper. There was a high correlation between area and volume. The range of maximum depths for a given area was high, however. Thus the mean of a few measurements of depths should not be used to calculate volume from area. At 24 hours, 77% of the rat, 47% of the rabbit and 28% of the chick lacunae were less than 1,000 microns 3 in volume; and 11% of the rat, 17% of the rabbit and 22% of the chick lacunae were between 1,000 and 2,000 microns 3 in volume. The mean values at 24 hours were 981, 2796, and 4582 microns 3 for rat, rabbit and chick lacunae respectively.

Embryos of C57B1/6J mice were examined grossly, and by light and scanning electron microscopy on days 8 through 19 of gestation. Adult eyes were examined by slit lamp biomicroscopy and light microscopy. A spontaneous incidence of eye malformations including microphthalmia, microphakia, corneal opacity and anterior segment dysgenesis was observed at a rate of 13.2% in the adults and 10.8% in the day 14 embryos. Scanning electron microscopy demonstrates the complex series of coordinated changes in shape and tissue interrelationships observed in normal ocular development. Possible routes of abnormal ocular morphogenesis beginning as early as the time of optic vesicle formation are discussed.

The basic function of the epidermis is to provide a barrier which will separate the body compartment from the environment thus protecting the organism from excessive loss of water and to hinder the entrance of noxious agents. A continuous renewal of the actual barrier makes it possible to fulfil these requirements. Using particle probe analysis, electron microprobe (EMP) and proton microprobe (PMP) analysis we have demonstrated the feasibility of these techniques in the study of skin physiology. The results reported here have been obtained on quench frozen skin specimens inertly prepared by cryotechniques to produce freeze-dried sections presenting cross sections of the skin. The distribution of Na and K is compatible with the idea that the Na/K pump of the cell membranes is dysfunctional above the basal cell layer. The phosphorus distribution over the epidermal cross section coincides with a previously shown phospholipid distribution. S and mass distributions correspond to the results of the keratin synthesis of the epidermis. Calcium displays a profile over the epidermis which is compatible with recent data obtained on the calcium dependence of the differentiation of epidermal cells in culture. Also this distribution corresponds to recent data obtained by histochemical methods at transmission electron microscope resolution. Zn and Fe have been shown to reside mainly in the basal cell layer of the normal epidermis but are found in high amounts in the outer cell layers of the epidermis in hyperproliferative paralesional psoriasis.(ABSTRACT TRUNCATED AT 250 WORDS)

In the present work, vessels casts in the inner ear of the rat and guinea pig, prepared by casting method using Mercox resin, were subjected to scanning electron microscopic examination and following results were obtained: In adult guinea pig, numerous capillary nets were found in the following parts: stria vascularis, spiral ligament, spiral prominence, Corti's organ, spiral ganglion, plexus cochlearis, semicircular ampulla, saccule, utricle, and endolymphatic sac. These were consistent with functionally and morophologically important areas in the inner ear. In the central side of the area with capillary nets, arterioles were found to run throughout, like a complex coil, and peripheral capillary diameter was found to be unchanged in an experiment in which the injection pressure was altered, thus autoregulation of blood flow into these important areas is assumed. Vessels in the planum semilunatum were found to form a specific loop-shaped route, where secretion and reabsorption of endolymph is thought to occur. After kanamycin injection into the tympanic cavity, stenosis was observed in capillary nets in the cochlear lateral wall. In guinea pigs on the 30th day of fetal life, the main stem of the inner ear vessel had already formed; however, the peripheral capillary nets were as yet immature in form and vessel density was low.

We have used scanning electron microscopy (SEM) to examine the surface morphology of the renal epithelial cell lines MDCK and LLC-PKl to determine the influence of alternative culture substrate conditions on cell polarity. We observed that regardless of physical culture conditions, cells established and maintained polarity, expressed by the characteristics of apical and basal surfaces. Culture conditions did, however, influence the orientation of cell polarity in vitro. MDCK cells were grown within collagen gel, in which individual cells exhibited clonal growth to form fluid-filled epithelial cysts. The cells of MDCK-cysts were polarized with apical surface facing the lumen and basal surface against the surrounding collagen gel. This configuration made it possible to gain direct visual access, by SEM, to the basal surface by removing the supportive collagen lattice. The apical surface of MDCK-cysts was lined by short microvilli. Each cell possessed a solitary cilium. In comparison, the basal surface had few appendages, although cell boundaries were marked by interdigitating short processes. LLC-PKl cells in monolayer culture bore solitary cilia and long microvilli at their apical surface. The basal surface of cells involved in dome formation was observed to possess only a sparse population of short, blunt processes. When LLC-PKl cells were raised in stationary suspension culture or in monolayer atop non-culture grade plastic, they formed cysts with the cell apex facing the surrounding medium. These cells showed variable apical morphology. The cells of large, highly expanded cysts were often attenuated and had a relatively smooth apical surface. The basal surface of cells of fractured LLC-PKl cysts commonly was also smooth, without prominent appendages.