Immunospecific labeling of mouse lymphocytes in the scanning electron microscope

Bone marrow-derived (B) and thymus-derived (T) Balb/c mouse lymphocytes were identified in the scanning electron microscope (SEM) by the immunospecific attachment of one of several kinds of large-molecular-weight markers distinguishable in SEM. These markers (tobacco mosaic virus, keyhole limpet hemocyanin, bushy stunt virus, and bacteriophage T4) could be modified with hapten groups and linked with anti-hapten antibody, in an indirect (sandwich) scheme, to hapten-modified anti-cell-surface antibody bound to the cell surface. Hapten-modified antibodies to B cell antigens (goat anti-mouse-immunoglobulin) or to T cell antigens (rabbit anti-mouse brain) were employed to identify these two lymphoid cell types in unfractionated spleen, mesenteric lymph node, bone marrow, and thymus cell populations. The topography of B cells was always indistinguishable from that of T cells. No surface features were found to be unique to either cell type. In suspension, the majority of B and T cells had one or no microvilli regardless of the tissue source of the labeled cells. Cells in suspension that had microvilli (usually 10% of the total cell population) were always unlabeled. However, after cell contact with a glass surface, approximately half of both the B and T cell populations had a villous topography.     

A scanning electron microscope study of mouse peritoneal mesothelium.

As seen in the scanning electron microscope, peritoneal mesothelial cells of the mouse diaphragm, anterior abdominal wall and intestinal serosa carry numerous microvilli. These microvilli are absent over certain areas of the cell surface and are sometimes, interlocked in meshwork patterns or coronal formation. The apical cell membranes of the mesothelium at the base of the microvilli, are invaginated by many plasmalemmal vesicles and vacuoles and carry a number of protruding spherical structures. Deep circular craters, giving the impression of stomata, are also visible.     

Variation in antennal sensilla of some hepialid moths; a scanning electron microscope study

Sensilla on the antennae of 5 species of hepialid moths—Aenetus virescens (Hepialinae) and Wiseana cervinata, W. signata, W. umbraculata, and Trioxycanus enysii (Oxycaninae)—were examined with the scanning electron microscope. Only 4 of the 6 types of sensilla previously described from noctuid moths were observed. The arrays of sensilla on oxycanine species are not uniformly distributed, especially on males; most of the sensors on any segment are on the ‘ridge’ of the pectinations, with a sparse distribution of relatively widely spaced sensors on the rest of the cuticle. In all species examined the antennae were sexually dimorphic; this was most apparent in the differing sensilla arrays of Hepialinae and in the difference in size of the antennal pectinations of Oxycaninae.     

A scanning electron microscope study of the extraembryonic endoderm of the 8th-day mouse embryo

Abstract. Late primitive streak embryos were dissected to reveal the junction between the visceral (VE) and parietal (PE) extraembryonic endoderm. Scanning electron microscopy showed that the two cell types differ markedly in their surface morphology and intercellular organization: the VE cells have numerous apical microvilli and form part of a continuous epithelial layer, while the smoother PE cells are scattered individually over the surface of Reichert's membrane. One interpretation of the morphology of the junction between the two tissues is that visceral endoderm cells in this region are detaching from the epithelial layer, migrating on to Reichert's membrane and differentiating into parietal endoderm. Preparatory to this, the visceral endoderm cells in the junctional zone may undergo extensive reorganization of their surface membranes.     

A scanning electron microscope study of microvascular anastomoses.

The abdominal aortas of 30 rats were sutured under an operating microscope. The results were studied under a scanning electron microscope at 8 different periods after operation, ranging from 3 minutes to one month. The observations are presented.     

Simultaneous visualization of myeloperoxidase reactivity and immunogold labeling by backscattered electron imaging with the scanning electron microscope

We describe a method to label circulating human granulocytes with an immunogold marker and then incubate them for demonstration of myeloperoxidase activity. The cells were observed in the backscattered electron imaging (BEI) mode of the scanning electron microscope. This permits simultaneous visualization of cell surface morphology, the immunological surface marker, and the cytochemical reactivity of each individual cell. Enhanced identification of the various cell types and more precise characterization of cell surface features in the different steps of leukocyte differentiation are expected to result from application of this technique.     

Mechanical wear of the gastropod radula: a scanning electron microscope study

The wear sustained by the teeth of the highly mineralized radula of Patella vulgata and the unmineralized radula of Agriolomax reticulatus has been studied with the scanning electron microscope. The unworn teeth of P. vulgata have tall pointed cusps and wear is first seen as a chipping of the tips then as abrasion. There is a well defined abraded surface giving the worn teeth a chisel shape. In cleaved teeth fibres ˜ 800 Å in diameter are observed parallel to the axis of the tooth. Evidence is presented for chemical etching and for the existence of a surface coat on the tooth. A. reticulatus teeth show wear over their whole surface. With the aid of the grooves in the jaw caused by the teeth the role of the jaw in flattening the radula and protracting and retracting the odontophore is confirmed. From the arrangement of the abraded surfaces on the teeth of P. vulgata it was deduced that the teeth rows are abraded one at a time while on a convex surface at or near the bending plane.     

Peritoneal fine structure of inguinal hernia: a scanning electron microscope study

Mesothelial cells of the normal human peritoneum of the anterior abdominal wall are covered with numerous surface microvilli. These cells become partially denuded inside the sacs of direct and indirect inguinal hernias and so lose the protective property the microvillar covering may impart on them. These mesothelial cells of hernial sacs also acquire an extensive surface coat of fibrin-like material, presumably due to the loss of that protective property, which may as a result subject them to adhesions. There is a considerable collagen build-up in the subserosal fibrous tissue of sacs of both direct and indirect inguinal hernias. Such a build-up is at variance with the accepted current surgical concept which suggests a defect in collagen synthesis, rather than a build-up, as the cause of direct hernia.     

The organization of the mammalian kinetochore: a scanning electron microscope study

Summary A procedure has been developed for scanning electron microscopy that enables the visualization of kinetochores along the surface of isolated chromosomes of the Indian muntjac. Indirect immunofluorescence and thin section analysis of the kinetochores of those isolated chromosomes verified that these structures retained in vivo composition and morphology during the isolation procedure. In scanning electron micrographs the outer surface of the outer kinetochore plate can be visualized as a series of fibers 25–30 nm in diameter that are arranged across the plate. These images are comparable to those obtained by whole mount transmission electron microscopic procedures (Rattner 1986) and are compatible with a model of the kinetochore in which chromatin fiber from the body of the chromosome extend to the outer kinetochore plate.     

Cosmos pollen ontogeny: A scanning electron microscope study

Summary Ontogenetic data concerning pollen not only clarifies the mode of deposition of the elaborate walls but has considerable functional and taxonomic relevance. Hitherto such studies have used optical or transmission electron microscopy but here a recently devised preparative technique has enabled pollen development inCosmos bipinnatus to be studied using the scanning electron microscope. The technique involves freeze-fracturing of osmium fixed, cryoprotected anthers, maceration in dilute osmium tetroxide, critical point drying, sputter coating and examination. The processes of pollen wall development can then be observed in three dimensions, an important aid to understanding the spatial relationships involved in the determination of ornamentation and apertures. Details of the pollen and tapetum are described at various stages between meiosis and anthesis. A close conformity is demonstrated between the results obtained and those of earlier transmission electron microscopic studies of the same and related species although very different interpretations are made.     

Kupffer's vesicle in Fundulus heteroclitus: a scanning and transmission electron microscope study

Kupffer's vesicle, a transitory organ peculiar to teleost embryos, was investigated in embryos of Fundulus heteroclitus by scanning electron microscopy. The roof of the vesicle is constructed to rather large columnar cells which are in continuity wiht hypoblast cells. Each of the roof cells is adorned with a single long cilium which emerges from a depression in the center of the surface and extends into the cavity of the vesicle. Studies with a transmission electron microscope confirm and extent these observations. The surface of the roof of the vesicle variously exhibits the presence of droplets and viscous and/or filamentous material. The exposed surface, however, sometimes appears clean and somtimes appears to have undergon partial destruction. The periblast floor of the vesicle is characterized by the presence of numerous folds and/or microvillus projections into the cavity of the vesicle. A filamentous precipitate is sometimes present. These observations are discussed in terms of the possible functional significance of this unique evanescent organ of the teleost embryo.     

A scanning electron microscope study of early sea urchin reaggregation

Sea urchin embryos were observed with SEM during the first 2 h of reaggregation, following dissociation of the 16-cell stage. A dense meshwork, composed of elongated microvilli embedded in the hyaline layer, surrounds the egg during early development. The dissociation procedure strips off some of the meshwork layer leaving fewer and smaller microvilli on the cell surface. Shortly after reaggregation has begun, several types of cell extensions are formed, including filopodia, which anchor the cells to the substrate, and ruffles and pseudopods, which enable the cells to move. Possible factors involved in the behavior of dissociated cells are discussed with regard to (1) the source of additional membrane in the formation of new cell extensions; (2) the ability of the cells to move.     

A scanning electron microscope study of human cerebral arteries.

Human cerebral arteries were obtained from autopsy, fixed under pressure, cut open, and tacked onto pieces of cork. For one artery the intima was partly teased away, exposing the media, and treated with a silver nitrate process. For another artery the adventitia was exposed. Both arteries were processed through graded ethanols and coated with gold paladium for the scanning electron microscope. The collagen fibers of the adventitia were approximately 5 mum in diameter and consisted of a bundle of microfilaments, each of which had a diameter of 800-1000 A (1 A = 10(-10) m). The collagen fibers were oriented parallel to the long axis of the artery. The muscle cells of the media had a diameter of 2-5 mum and were arranged circumferentially with a pitch of approximately 20 degrees. The collagen fibers of the media travel perpendicular to the muscle cells, and parallel to the long axis of the artery. The fibrillar components of the elastin in the intima had a diameter of approximately 700-1000 A and were arranged parallel to the long axis of the artery. It was postulated that the fibrillar part of the elastin was the elastic component of the elastin.     

Cuticular morphology of five species of Dirofilaria: a scanning electron microscope study

Cuticular markings of five species of Dirofilaria were examined by SEM. Variations in the patterns on the en face view were observed among the species. Transverse striations were observed on the cuticles of all five species, but longitudinal ridges were lacking on Dirofilaria immitis, the type species of the subgenus Dirofilaria. They were present on the other four species, Dirofilaria repens, Dirofilaria tenuis, Dirofilaria corynodes, and Dirofilaria magnilarvatum, members of the subgenus Nochtiella. Longitudinal ridges and other cuticular structures and patterns were seen to vary among the species and with the portion and aspect of the worm examined. It is suggested that SEM would be a good tool for a detailed study of specific cuticular morphology of all species of Dirofilaria, thus contributing toward their differentiation and recognition.