Ultramorphological Characteristics of Podocyte Development in the Human Fetal Metanephros

2018 ◽  
Vol 205 (1) ◽  
pp. 42-52
Author(s):  
Marija Dakovic Bjelakovic ◽  
Slobodan Vlajkovic ◽  
Milica Bjelakovic
Keyword(s):  
Electron Microscopy ◽  
Close Contact ◽  
Apical Surface ◽  
Capillary Loop ◽  
Shaped Body ◽  
Initial Separation ◽  
Transmission Electron ◽  
Developmental Characteristics ◽  
Degree Of Differentiation ◽  
Cytoplasmic Processes

The aim of this study was to determine the developmental characteristics of podocytes in the human fetal metanephros using scanning electron microscopy, light microscopy, and transmission electron microscopy. Kidney samples of 15 human fetuses of both sexes (gestational age 10–22 weeks) were analyzed. At the S-shaped body stage, primitive podocytes were arranged in a layer of cuboidal cells beneath the vascular cleft. When observed from Bowman’s space, the demarcation between adjacent podocytes was not clear, but mild depressions indicated cell boundaries. At the more advanced S-shaped body stage, podocytes were polygonal, with a flat apical surface. They were in close contact, but boundaries between adjacent cells were distinct. After initial separation of their apical parts, podocytes continued to separate from each other along their lateral sides. Their shape changed from polygonal to spherical, resembling clusters of grapes. Cytoplasmic buds could be seen at the base of some podocytes initially, when all podocytes were spherical. Parallel with the development of the first capillary loops, wider intercellular spaces were noted between elliptical-shaped podocytes. Podocytes then developed cytoplasmic processes and became flattened and star shaped. Their cell bodies separated from the glomerular basement membrane through the insertion of thick processes under the cell body. Thick primary processes ramified to form the foot processes, which interdigitated on the surface of capillary loops. During the capillary loop stage, the degree of differentiation of the podocytes varied among various glomerular regions, as well as within the same capillary loop.

The translaminal fibrils of the human amnion basement membrane

1989 ◽  
Vol 94 (2) ◽  
pp. 307-318
Author(s):  
S. Campbell ◽  
T.D. Allen ◽  
B.B. Moser ◽  
J.D. Aplin
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Surface ◽  
Basal Lamina ◽  
Ammonium Hydroxide ◽  
Apical Surface ◽  
Lamina Densa ◽  
Transmission Electron ◽  
Extraction Pattern ◽  
Stromal Matrix

The organisation of extracellular matrix beneath the human amniotic epithelium was investigated in order that the co-ordinate synthesis of basal lamina and stroma by these cells could be better understood. Transmission electron microscopy of intact tissue confirmed that stromal matrix fibrils are located between the cell surface and the basal lamina, and also penetrate the lamina. The distribution of the supralaminal fibrils and their association with the lamina was further investigated by scanning electron microscopy (SEM) after removal of the overlying epithelium. Five complementary procedures were used to remove the cells from the underlying lamina. Trypsin-EDTA treatment caused the epithelial cells to retract or detach from the lamina. SDS or ammonium hydroxide was used to extract the epithelium, which was then removed by physical shearing. Transmission electron microscopy (TEM) confirmed that the lamina densa and supralaminal fibres were present after extraction by these agents. Incubation in CHAPS, a zwiterionic detergent, did not remove the epithelium but permitted exposure of the basal lamina by mechanical scoring. Extraction with boric acid followed by osmium tetroxide produced epithelial disruption and revealed the lamina and stroma in different areas. Although the extraction pattern was different in each case, all of the five methods confirmed that individual fibrils and fibril bundles are present on the apical surface of, and enter, the lamina densa. Examination of the stromal surface of the basal lamina after fracture revealed fibrils passing from the stroma into the lamina densa. We therefore suggest that, in this tissue, newly synthesised stromal matrix components appear in an assembled fibrillar form between the basal cell surface and the basal lamina before becoming associated with the sublaminal stroma.

Antigen-presenting Cells in Human Radicular Granulomas

2008 ◽  
Vol 87 (6) ◽  
pp. 553-557 ◽  
Author(s):  
T. Kaneko ◽  
T. Okiji ◽  
R. Kaneko ◽  
J.E. Nör ◽  
H. Suda
Keyword(s):  
Electron Microscopy ◽  
T Cells ◽  
Dendritic Cells ◽  
Antigen Presenting Cells ◽  
Gold Particles ◽  
Immunological Responses ◽  
Hla Dr ◽  
Transmission Electron ◽  
Antigen Presenting ◽  
Cytoplasmic Processes

Substantial numbers of dendritic cells have been detected in radicular granulomas. To test the hypothesis that local antigen presentation from dendritic cells to T-cells is involved critically in immunological responses within radicular granulomas, we compared characteristics of dendritic cells and macrophages by morphological and biological analyses. Under light microscopy, HLA-DR+ and CD68+ cells showed diverse profiles, including dendritic-shaped cells. Transmission electron microscopy revealed that HLA-DR+ dendritic cells, with long cytoplasmic processes and lacking distinct phagosomes, were concentrated in the lymphocyte-rich area. HLA-DR alpha-chain, CD83, and CD86 mRNAs from HLA-DR+ dendritic cells, and CD28 mRNA from CD28+ T-cells were up-regulated in lymphocyte-rich area. Scanning electron microscopy demonstrated that the density of gold particles on dendritic cells was higher than that on HLA-DR+ macrophages. These results suggest that dendritic cells in radicular granulomas are associated with local defense reactions as stronger antigen-presenting cells, as compared with macrophages.

Localization of microfilament bundles in the upper layer of the primitive-streakstage chick blastoderm

Development ◽  
1982 ◽  
Vol 67 (1) ◽  
pp. 59-70
Author(s):  
L. Vakaet ◽  
Ch. Vanroelen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Close Association ◽  
Primitive Streak ◽  
Neural Plate ◽  
Junctional Complex ◽  
Apical Surface ◽  
Chick Blastoderm ◽  
Transmission Electron ◽  
Microfilament Bundles

Transmission electron microscopy of medium-streak-stage chick blastoderms revealed the presence of 4–6 nm microfilament bundles just under the apical surface of upper layer cells, in close association with the junctional complex. The presence of these microfilament bundles was not restricted to the centre of the primitive streak, but they were also observed in the presumptive neural plate and lateral to the anterior half of the primitive streak. The microfilament bundles are thought to be involved in every morphogenetic movement in the upper layer and not to be restricted to groove formation.

Aspects ultrastructuraux de l'interaction uretère-mesenchyme, au cours de l'induction néphrogène, chez les amphibiens

Development ◽  
1977 ◽  
Vol 41 (1) ◽  
pp. 259-268
Author(s):  
Par J.-D. Gipouloux ◽  
M. Delbos
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Extracellular Matrix ◽  
Close Contact ◽  
Close Apposition ◽  
Collagen Fibres ◽  
Morphological Basis ◽  
Transmission Electron

Ultrastructural features of ureter-mesenchyme interaction, during nephrogenic induction in Amphibia Transmission electron microscopy was used to study the interface between the ureter and the mesonephric blastema. When the blastema is induced in a functional organ, numerous pseudopodial protrusions of the ureter and of the mesonephric cells lead to a close apposition between the two structures. The presence of squamous material, perhaps of a mucopolysaccharidic nature, with a network of collagen fibres is always found on this interface. These particular processes seem to play a role as a morphological basis for the phenomenon of induction. The importance of the extracellular matrix is discussed. Neither the occurrence of zones of close contact, reported by several authors, in other species, nor the fusion of membranes has ever been observed, in Amphibia.

Electron microscopy of platelet interactions with heme-octapeptide-labeled fibrinogen

1990 ◽  
Vol 259 (4) ◽  
pp. C611-C618 ◽  
Author(s):  
D. G. Moon ◽  
J. R. Shainoff ◽  
S. R. Gonda
Keyword(s):  
Electron Microscopy ◽  
Close Contact ◽  
Factor Xiiia ◽  
Platelet Surface ◽  
Binding Domains ◽  
Transmission Electron ◽  
Platelet Binding ◽  
Nonspecific Staining ◽  
Platelet Aggregates ◽  
Fibrinogen Molecule

Binding of fibrinogen to ADP-activated platelets was visualized by labeling the molecule with heme-octapeptide (microperoxidase) for direct cytochemical staining. Transmission electron microscopy of the platelet aggregates showed most of the fibrinogen distributed widely over the platelet surface in nonbridging rims of 7- to 9-nm thickness. Short peroxidase-positive bridges (less than 25 nm) were found in clusters in regions of close contact between the platelets, but 50-nm bridging corresponding to the length of the molecule was not seen by this method. Thus the fibrinogen appeared to be binding in a predominantly prone rather then upright orientation on the platelets. Abundant 50-nm bridging seen by nonspecific staining appeared unrelated to the length of the fibrinogen molecule because the bridging did not change when the length of the fibrinogen was more than doubled by end-to-end cross-linking with factor XIIIa. It is suggested that the observed binding and bridging of fibrinogen in a prone orientation is promoted by the existence of multiple platelet-binding domains on the molecule.

Pigment epithelial ensheathment and phagocytosis of extrafoveal cones in human retina

1977 ◽  
Vol 277 (958) ◽  
pp. 459-471 ◽  
Keyword(s):  
Electron Microscopy ◽  
Outer Segment ◽  
Pigment Epithelium ◽  
Apical Surface ◽  
Human Retina ◽  
Pigment Epithelial ◽  
Transmission Electron ◽  
Intracellular Organelles ◽  
Pigment Epithelial Cells ◽  
Scanning Electron

The association between extrafoveal cone outer segments and pigment epithelial cells was studied by transmission electron microscopy in three human retinas; ages 5, 45 and 60. The pigment epithelial apical surface from a fourth human retina, age 38, was viewed in the scanning electron microscope. Multiple villous-like apical processes protrude from the pigment epithelium into the space above each cone. Sometimes one or more of these processes is sheet-like in form and contains a wealth of intracellular organelles, including mitochondria. One or more of the villous-like procesess reaches the cone and expands to ensheath the upper one-third of the outer segment. Like vertebrate rods, extrafoveal human cones shed their terminal disks in packets and these packets are phagocytosed by the ensheathing apical processes. The phagosomes then ascend in the processes toward the pigment epithelia soma. Digestion of phagosomes appears to begin in the apical processes.

Primary Intraosseous Malignant Meningioma of the Skull: Case Report

Neurosurgery ◽  
1988 ◽  
Vol 23 (4) ◽  
pp. 505-508 ◽  
Author(s):  
Wei-Hwa Lee ◽  
Yen-Chang Tu ◽  
Ming-Yin Liu
Keyword(s):  
Electron Microscopy ◽  
Cultured Cells ◽  
Positive Staining ◽  
Malignant Meningioma ◽  
Osteolytic Lesions ◽  
Transmission Electron ◽  
S 100 ◽  
Immunocytochemical Studies ◽  
Intraosseous Meningioma ◽  
Cytoplasmic Processes

Abstract Primary intraosseous meningioma of the skull is rare. This report describes a 61-year-old man who was treated by craniectomy 3 times for a repeatedly recurrent primary intraosseous malignant meningioma. Transmission electron microscopy revealed interdigitation of cytoplasmic processes, microfilaments, and distinct desmosomal structures. Immunocytochemical studies of cultured cells showed strong expression of vimentin and weakly positive staining for S-100 protein. Primary intraosseous malignant meningioma should be considered in the differential diagnosis of massive solitary osteolytic lesions of the skull.

Maxillary Sinus Augmentation Using an Engineered Porous Hydroxyapatite: A Clinical, Histological, and Transmission Electron Microscopy Study in Man

10.1563/796.1 ◽  
2006 ◽  
Vol 32 (3) ◽  
pp. 122-131 ◽  
Author(s):  
Carlo Mangano ◽  
Antonio Scarano ◽  
Giovanna Iezzi ◽  
Giovanna Orsini ◽  
Vittoria Perrotti ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Light Microscopy ◽  
Maxillary Sinus ◽  
Close Contact ◽  
Inflammatory Cell Infiltrate ◽  
Sinus Augmentation ◽  
Porous Hydroxyapatite ◽  
Maxillary Sinus Augmentation ◽  
Transmission Electron

Abstract Porous hydroxyapatite (HA) is a calcium-phosphate–based material that is biocompatible, nonimmunological, and osteoconductive, and has a macroporosity of about 200 to 800 μm. The pores seem to be able to induce migration, adhesion, and proliferation of osteoblasts inside the pore network and to promote angiogenesis inside the pore system. The aim of this study was to evaluate the clinical behavior and the histological and ultrastructural aspects of porous HA in maxillary sinus augmentation procedures. Twenty-four patients (19 men, 5 women; average age 53.4 years) in good general physical and mental health and with partially or completely edentulous maxillae were selected for this study. Six months after sinus floor elevation, at the time of dental implant placement, biopsies were carried out under local anesthesia. These bone cores were cut in half and were processed for light and transmission electron microscopy. After a mean 3 years after implantation, all implants are clinically in function and no surgical or prosthetic complications have occurred. Under light microscopy, newly formed bone was 38.5% ± 4.5%, whereas the residual biomaterial represented 12% ± 2.3% and the marrow spaces represented 44.6% ± 4.2%. In addition, in the majority of cases, the biomaterial particles were in close contact with the bone, which appeared compact with the characteristic features of well-organized lamellar bone. A cement-like line was slightly visible at the bone-biomaterial interface, but there were no gaps or interposed connective tissue in between. A high quantity (about 40%) of newly formed bone was present. Bone was closely apposed to the biomaterials particles as shown in light microscopy and transmission electron microscopy. Moreover, no signs of inflammatory cell infiltrate or foreign body reaction were present. Also, most of the biomaterial was resorbed and only a small quantity (a little more than 10%) was still present. The results of our study show that porous HA can be a suitable synthetic material for bone regeneration in maxillary sinus augmentation procedures.

Techniques for Transmission Electron Microscopy of Fiber-Matrix Interfaces in Aluminum Alloy-Boron Composites by Ion Erosio

1971 ◽  
Vol 29 ◽  
pp. 204-205
Author(s):  
G. G. Shaw
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Aluminum Alloy ◽  
Electron Beam ◽  
Pure Aluminum ◽  
Ion Milling ◽  
Transmission Electron ◽  
Fiber Matrix ◽  
Ion Erosion ◽  
Row Of Fibers

The morphology and composition of the fiber-matrix interface can best be studied by transmission electron microscopy and electron diffraction. For some composites satisfactory samples can be prepared by electropolishing. For others such as aluminum alloy-boron composites ion erosion is necessary.When one wishes to examine a specimen with the electron beam perpendicular to the fiber, preparation is as follows: A 1/8 in. disk is cut from the sample with a cylindrical tool by spark machining. Thin slices, 5 mils thick, containing one row of fibers, are then, spark-machined from the disk. After spark machining, the slice is carefully polished with diamond paste until the row of fibers is exposed on each side, as shown in Figure 1.In the case where examination is desired with the electron beam parallel to the fiber, preparation is as follows: Experimental composites are usually 50 mils or less in thickness so an auxiliary holder is necessary during ion milling and for easy transfer to the electron microscope. This holder is pure aluminum sheet, 3 mils thick.

Direct Observation of Heat Exchanger Deposits by Cross Sectioning

1967 ◽  
Vol 25 ◽  
pp. 364-365
Author(s):  
R. W. Anderson ◽  
D. L. Senecal
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Heat Exchanger ◽  
Direct Observation ◽  
Cross Sections ◽  
Preparation Method ◽  
Specimen Preparation ◽  
Flowing Water ◽  
Transmission Electron ◽  
Deposit Layer

A problem was presented to observe the packing densities of deposits of sub-micron corrosion product particles. The deposits were 5-100 mils thick and had formed on the inside surfaces of 3/8 inch diameter Zircaloy-2 heat exchanger tubes. The particles were iron oxides deposited from flowing water and consequently were only weakly bonded. Particular care was required during handling to preserve the original formations of the deposits. The specimen preparation method described below allowed direct observation of cross sections of the deposit layers by transmission electron microscopy.The specimens were short sections of the tubes (about 3 inches long) that were carefully cut from the systems. The insides of the tube sections were first coated with a thin layer of a fluid epoxy resin by dipping. This coating served to impregnate the deposit layer as well as to protect the layer if subsequent handling were required.

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