scholarly journals An Electron Microscopic Study of the Intestinal Villus

1959 ◽  
Vol 5 (3) ◽  
pp. 363-371 ◽  
Author(s):  
Sanford L. Palay ◽  
Leonard J. Karlin
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Epithelial Cell ◽  
Basement Membrane ◽  
Lamina Propria ◽  
Nerve Fibers ◽  
Apical Surface ◽  
Intestinal Villus ◽  
Thin Sections ◽  
Blood Capillaries

The structure of the intestinal villus of the rat was studied in thin sections of tissue fixed in buffered osmium tetroxide and embedded in methacrylate. The simple columnar epithelium investing the villus is surmounted by a striated border consisting of slender projections of the cell surface. These microvilli are arranged in almost crystalline, hexagonal array, and increase the apical surface area of the cell by a factor of 24. The core of each microvillus is filled with fine fibrils which arise from the filamentous substance of the terminal web underlying the striated border. Each microvillus is covered by a tubular extension of the plasma membrane of the epithelial cell. Pinocytotic vesicles originating from the plasma membrane occur at the bases of the intermicrovillous spaces. The nucleus, mitochondria, and the endoplasmic reticulum of the epithelial cell display no unusual features. Small bits of ergastoplasm occur in the apical cytoplasm. A thin basement membrane separates the epithelium from the lamina propria which consists of vessels, nerves, and numerous lymphocytes, eosinophiles, mast cells, plasma cells, smooth muscle fibers, and macrophages suspended in a delicate stroma of fibroblasts and collagen fibers. Intercellular fat droplets often occur in this stroma, even in animals fasted for 40 hours. The blood capillaries are distinguished by their extremely attenuated, fenestrated endothelial cells. The lacteal has a thicker endothelium which, although not fenestrated, appears to have significant interruptions, especially at the margins between neighboring lining cells. Strands of smooth muscle always accompany the lacteal but do not form an integral part of its wall. Unmyelinated nerves, many of which are too small to be distinguished with the light microscope, course through the lamina propria in association with the vessels. The nerve fibers evidently do not cross the basement membrane into the epithelium. Neuromuscular junctions or other terminal apparatus were not found.

scholarly journals THE FINE STRUCTURE OF THE TRANSITIONAL EPITHELIUM OF RAT URETER

1965 ◽  
Vol 26 (1) ◽  
pp. 25-48 ◽  
Author(s):  
R. M. Hicks
Keyword(s):  
Plasma Membrane ◽  
Fine Structure ◽  
Basement Membrane ◽  
Transitional Epithelium ◽  
Permeability Barrier ◽  
Basal Cells ◽  
Thin Sections ◽  
Squamous Cells ◽  
Intermediate Cells ◽  
Nucleoside Triphosphatase

The fine structure of the transitional epithelium of rat ureter has been studied in thin sections with the electron microscope, including some stained cytochemically to show nucleoside triphosphatase activity. The epithelium is three to four cells deep with cuboidal or columnar basal cells, intermediate cells, and superficial squamous cells. The basal cells are attached by half desmosomes, or attachment plates, on their basal membranes to a basement membrane which separates the epithelium from the lamina propria. Fine extracellular fibres, ca. 100 A in diameter, are to be found in the connective tissue layer immediately below the basement membrane of this epithelium. The plasma membranes of the basal and intermediate cells and the lateral and basal membranes of the squamous cells are deeply interdigitated, and nucleoside triphosphatase activity is associated with them. All the cells have a dense feltwork of tonofilaments which ramify throughout the cytoplasm. The existence of junctional complexes, comprising a zonula occludens, zonula adhaerens, and macula adhaerens or desmosome, between the lateral borders of the squamous cells is reported. It is suggested that this complex is the major obstacle to the free flow of water from the extracellular spaces into the hypertonic urine. The free luminal surface of the squamous cells and many cytoplasmic vesicles in these cells are bounded by an unusually thick plasma membrane. The three leaflets of this unit membrane are asymmetric, with the outer one about twice as thick as the innermost one. The vesicles and the plasma membrane maintain angular conformations which suggest the membrane to be unusually rigid. No nucleoside triphosphatase activity is associated with this membrane. Arguments are presented to support a suggestion that this thick plasma membrane is the morphological site of a passive permeability barrier to water flow across the cells, and that keratin may be included in the membrane structure. The possible origin of the thick plasma membrane in the Golgi complex is discussed. Bodies with heterogeneous contents, including characteristic hexagonally packed stacks of thick membranes, are described. It is suggested that these are "disposal units" for old or surplus thick membrane. A cell type is described, which forms only 0.1 to 0.5 per cent of the total cell population and contains bundles of tubular fibres or crystallites. Their origin and function are not known.

Expression of caveolin-1 and polarized formation of invaginated caveolae in Caco-2 and MDCK II cells

1998 ◽  
Vol 111 (6) ◽  
pp. 825-832 ◽  
Author(s):  
U. Vogel ◽  
K. Sandvig ◽  
B. van Deurs
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Epithelial Cell ◽  
Basolateral Membrane ◽  
Apical Surface ◽  
Wild Type ◽  
Caveolin 1 ◽  
Endogenous Level ◽  
Epithelial Cell Lines ◽  
Different Levels

We have studied caveolin-1 expression and the frequency and distribution of typical invaginated caveolae as they are identified by electron microscopy in the polarized epithelial cell lines MDCK II and Caco-2. In wild-type MDCK II cells caveolin expression is high and more than 400 caveolae/mm filter were observed at the basolateral membrane. No caveolae were found at the apical surface. By contrast, wild-type Caco-2 cells do not express caveolin-1 and have extremely few, if any caveolae. Caco-2 cells were stably transfected with the gene for caveolin-1 in order to investigate if the formation of caveolae is polarized also in these cells. We have isolated Caco-2 clones expressing different levels of caveolin-1, where the level of expression varies from 10–100% of the endogenous level in MDCK II cells. Caveolin-1 expression in Caco-2 cells gives rise to a marked immunofluorescense labeling mainly at the lateral plasma membrane. By electron microscopy an increase from less than 4 caveolae/mm filter in wild-type Caco-2 cells to 21–76 caveolae/mm filter in Caco-2 clones transfected with caveolin-1 was revealed and these caveolae were exclusively localized to the basolateral membrane. Thus expression of heterologous caveolin-1 in Caco-2 cells leads to polarized formation of caveolae, but there is a lack of correlation between the amount of caveolin expressed in the cells and the number of caveolae, suggesting that factors in addition to caveolin are required for generation of caveolae.

scholarly journals Selective anchoring in the specific plasma membrane domain: a role in epithelial cell polarity.

1988 ◽  
Vol 107 (6) ◽  
pp. 2363-2376 ◽  
Author(s):  
P J Salas ◽  
D E Vega-Salas ◽  
J Hochman ◽  
E Rodriguez-Boulan ◽  
M Edidin
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cell ◽  
Fluorescence Recovery ◽  
Apical Surface ◽  
Collagen Gels ◽  
Surface Polarity ◽  
Basal Surface ◽  
Apical Domain ◽  
Cell Biol ◽  
In Cells

We have studied the role of restrictions to lateral mobility in the segregation of proteins to apical and basolateral domains of MDCK epithelial cells. Radioimmunoassay and semiquantitative video analysis of immunofluorescence on frozen sections showed that one apical and three basolateral glycoproteins, defined by monoclonal antibodies and binding of beta-2-microglobulin, were incompletely extracted with 0.5% Triton X-100 in a buffer that preserves the cortical cytoskeleton (Fey, E. G., K. M. Wan, and S. Penman. 1984. J. Cell Biol. 98:1973-1984; Nelson, W. T. and P. J. Veshnock. 1986. J. Cell Biol. 103:1751-1766). The marker proteins were preferentially extracted from the "incorrect" domain (i.e., the apical domain for a basolateral marker), indicating that the cytoskeletal anchoring was most effective on the "correct" domain. The two basolateral markers were unpolarized and almost completely extractable in cells prevented from establishing cell-cell contacts by incubation in low Ca++ medium, while an apical marker was only extracted from the basal surface under the same conditions. Procedures were developed to apply fluorescent probes to either the apical or the basolateral surface of live cells grown on native collagen gels. Fluorescence recovery after photobleaching of predominantly basolateral antigens showed a large percent of cells (28-52%) with no recoverable fluorescence on the basal domain but normal fluorescence recovery on the apical surface of most cells (92-100%). Diffusion coefficients in cells with normal fluorescence recovery were in the order of 1.1 x 10(-9) cm2/s in the apical domain and 0.6-0.9 x 10(-9) cm2/s in the basal surface, but the difference was not significant. The data from both techniques indicate (a) the existence of mobile and immobile protein fractions in both plasma membrane domains, and (b) that linkage to a domain specific submembrane cytoskeleton plays an important role in the maintenance of epithelial cell surface polarity.

scholarly journals Myosin-1a powers the sliding of apical membrane along microvillar actin bundles

2007 ◽  
Vol 177 (4) ◽  
pp. 671-681 ◽  
Author(s):  
Russell E. McConnell ◽  
Matthew J. Tyska
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cell ◽  
Apical Membrane ◽  
Membrane Vesicles ◽  
Cell Types ◽  
Intestinal Lumen ◽  
Apical Surface ◽  
Actin Bundle ◽  
Actin Bundles ◽  
Membrane Protrusions

Microvilli are actin-rich membrane protrusions common to a variety of epithelial cell types. Within microvilli of the enterocyte brush border (BB), myosin-1a (Myo1a) forms an ordered ensemble of bridges that link the plasma membrane to the underlying polarized actin bundle. Despite decades of investigation, the function of this unique actomyosin array has remained unclear. Here, we show that addition of ATP to isolated BBs induces a plus end–directed translation of apical membrane along microvillar actin bundles. Upon reaching microvillar tips, membrane is “shed” into solution in the form of small vesicles. Because this movement demonstrates the polarity, velocity, and nucleotide dependence expected for a Myo1a-driven process, and BBs lacking Myo1a fail to undergo membrane translation, we conclude that Myo1a powers this novel form of motility. Thus, in addition to providing a means for amplifying apical surface area, we propose that microvilli function as actomyosin contractile arrays that power the release of BB membrane vesicles into the intestinal lumen.

Localization of cholinergic nerves in lower airways of guinea pigs using antisera to choline acetyltransferase

1997 ◽  
Vol 272 (4) ◽  
pp. L731-L738 ◽  
Author(s):  
B. J. Canning ◽  
A. Fischer
Keyword(s):  
Smooth Muscle ◽  
Nerve Cell ◽  
Lamina Propria ◽  
Airway Smooth Muscle ◽  
Choline Acetyltransferase ◽  
Muscle Tone ◽  
Nerve Fibers ◽  
Specific Marker ◽  
Cholinergic Nerves ◽  
Peripheral Airways

Primary antiserum to choline acetyltransferase (ChAT), a specific marker for cholinergic nerves, was used to characterize the distribution of cholinergic nerve fibers and nerve cell bodies in guinea pig airways. ChAT immunoreactive nerve fibers were localized to the smooth muscle throughout the conducting airways and in the lamina propria of the trachea and large bronchi. Likewise, all nerve cell bodies in the ganglia intrinsic to the trachea and bronchi displayed a cholinergic phenotype. By contrast, ChAT immunoreactive nerve fibers were infrequently seen in the lamina propria of the peripheral airways and were absent in the airway epithelium. No evidence for colocalization of ChAT and the enzyme synthesizing the putative relaxant neurotransmitter nitric oxide was observed. These results provide further evidence for the key role played by cholinergic nerves in regulating airway smooth muscle tone and bronchial blood flow and provide further evidence that acetylcholine is not coreleased with the neurotransmitter(s) mediating relaxations of airway smooth muscle.

scholarly journals An Electron Microscopic Study of the Intestinal Villus

1959 ◽  
Vol 5 (3) ◽  
pp. 373-384 ◽  
Author(s):  
Sanford L. Palay ◽  
Leonard J. Karlin
Keyword(s):  
Endoplasmic Reticulum ◽  
Epithelial Cell ◽  
Lamina Propria ◽  
Corn Oil ◽  
Fat Absorption ◽  
Electron Microscopic ◽  
Thin Sections ◽  
Sudan Black B ◽  
Maximal Diameter ◽  
Pinocytotic Vesicles

The intestinal pathway for absorbed fat was traced in thin sections of intestinal villi from rats fed corn oil by stomach tube after a fast of 24 to 40 hours. For electron microscopy the tissues were fixed in chilled buffered osmium tetroxide and embedded in methacrylate. For light microscopy, other specimens from the same animals were fixed in formal-calcium, mordanted in K2Cr2O7, and embedded in gelatin. Frozen sections were stained with Sudan black B or Sudan IV. About 20 minutes after feeding, small fat droplets (65 mµ maximal diameter) appear in the striated border between microvilli. At the same time fat particles are seen within pinocytotic vesicles in the immediately subjacent terminal web. In later specimens the fat droplets are generally larger (50 to 240 mµ) and lie deeper in the apical cytoplasm. All intracellular fat droplets are loosely enveloped in a thin membrane, the outer surface of which is sometimes studded with the fine particulate component of the cytoplasm. This envelope, apparently derived from the cell surface by pinocytosis, has at this stage evidently become a part of the endoplasmic reticulum. Just above the nucleus numerous fat droplets lie clustered within the dilated cisternae of the Golgi complex. As absorption progresses fat droplets appear in the intercellular spaces of the epithelium, in the interstitial connective tissue spaces of the lamina propria, and in the lumen of the lacteals. All of these extracellular fat droplets are devoid of a membranous envelope. The picture of fat absorption as reconstructed from these studies involves a stream of fat droplets filtering through the striated border, entering the epithelial cell by pinocytosis at the bases of the intermicrovillous spaces, and coursing through the endoplasmic reticulum to be discharged at the sides of the epithelial cell into extracellular spaces. From the epithelial spaces, the droplets move into the lamina propria and thence into the lymph. If the lumen of the endoplasmic reticulum is considered as continuous with the extracellular phase, then the entire pathway of fat absorption may be regarded as extracellular. However, it is impossible to evaluate from the electron microscopic evidence thus far available the quantitative importance of particulate fat absorption by the mechanism described.

Scanning Electron Microscopy of Human Jejunum in Whipple's Disease

1977 ◽  
Vol 35 ◽  
pp. 354-355
Author(s):  
John H. L. Watson ◽  
C. N. Sun
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Basement Membrane ◽  
Lamina Propria ◽  
Brush Border ◽  
Whipple’S Disease ◽  
Whipple's Disease ◽  
Biopsy Specimens ◽  
Brush Borders ◽  
Scanning Electron

That the etiology of Whipple's disease could be bacterial was first suggested from electron micrographs in 1960. Evidence for binary fission of the bacteria, their phagocytosis by histiocytes in the lamina propria, their occurrence between and within the cells of the epithelium and on the brush border of the lumen were reported later. Scanning electron microscopy has been applied by us in an attempt to confirm the earlier observations by the new technique and to describe the bacterium further. Both transmission and scanning electron microscopy have been used concurrently to study the same biopsy specimens, and transmission observations have been used to confirm those made by scanning.The locations of the brush borders, the columnar epithelial cells, the basement membrane and the lamina propria beneath it were each easily identified by scanning electron microscopy. The lamina propria was completely filled with the wiener-shaped bacteria, Fig. 1.

An Ultrastructural Study of Pericytes

1968 ◽  
Vol 26 ◽  
pp. 66-67
Author(s):  
T. M. Murad ◽  
E. von Haam
Keyword(s):  
Plasma Membrane ◽  
Endothelial Cell ◽  
Basement Membrane ◽  
Blood Vessel ◽  
Vascular Endothelial Cells ◽  
Myoepithelial Cells ◽  
Capillary Blood ◽  
The Body ◽  
Capillary Blood Vessel ◽  
Outer Plasma Membrane

Pericytes are vascular satellites present around capillary blood vessels and small venules. They have been observed in almost every tissue of the body and are thought to be related to vascular smooth muscle cells. Morphologically pericytes have great similarity to vascular endothelial cells and also slightly resemble myoepithelial cells.The present study describes the ultrastructural morphology of pericytes in normal breast tissue and in benign tumor of the breast. The study showed that pericytes are ovoid or elongated cells separated from the endothelial cell of the capillary blood vessel by the basement membrane of endothelial cell. The nuclei of pericytes are often very distinctive. Although some are round, oval, or elongated, others show marked irregularity and infolding of the nuclear membrane. The cytoplasm shows mono-or bipolar extension in which the cytoplasmic organelles are located (Fig. 1). These cytoplasmic extensions embrace the capillary blood vessel incompletely. The plasma membrane exhibits multiple areas of focal condensation called hemidesmosomes (Fig. 2, arrow). A variable number of pinocytotic vesicles are frequently seen lining the outer plasma membrane. Normally pericytes are surrounded by a basement membrane which is found more consistently on the outer plasma membrane separating the pericytes from the stromal connective tissue.

Immunogold localization of HMB-45 antigen in pulmonary lymphangiomyomatosis

1995 ◽  
Vol 53 ◽  
pp. 998-999
Author(s):  
J.M. Minda ◽  
E. Dessy ◽  
G. G. Pietra
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Room Temperature ◽  
Osmium Tetroxide ◽  
Muscle Cells ◽  
Ultrastructural Localization ◽  
Reproductive Age ◽  
Thin Sections ◽  
Smooth Muscle Proliferation ◽  
Hmb 45

Pulmonary lymphangiomyomatosis (PLAM) is a rare disease occurring exclusively in women of reproductive age. It involves the lungs, lymph nodes and lymphatic ducts. In the lungs, it is characterized by the proliferation of smooth muscle cells around lymphatics in the bronchovascular bundles, lobular septa and pleura The nature of smooth muscle proliferation in PLAM is still unclear. Recently, reactivity of the smooth muscle cells for HMB-45, a melanoma-related antigen has been reported by immunohistochemistry. The purpose of this study was the ultrastructural localization of HMB-45 immunoreactivity in these cells using gold-labeled antibodies.Lung tissue from three cases of PLAM, referred to our Institution for lung transplantation, was embedded in either Poly/Bed 812 post-fixed in 1% osmium tetroxide, or in LR White, without osmication. For the immunogold technique, thin sections were placed on Nickel grids and incubated with affinity purified, monoclonal anti-melanoma antibody HMB-45 (1:1) (Enzo Diag. Co) overnight at 4°C. After extensive washing with PBS, grids were treated with Goat-anti-mouse-IgG-Gold (5nm) (1:10) (Amersham Life Sci) for 1 hour, at room temperature.

vitreal cells and specialized phagocytes in the chick embryo retina: A TEM and SEM study

1990 ◽  
Vol 48 (3) ◽  
pp. 330-331
Author(s):  
M.A. Cuadros ◽  
M.J. Martinez-Guerrero ◽  
A. Rios
Keyword(s):  
Cell Death ◽  
Plasma Membrane ◽  
Acid Phosphatase ◽  
Chick Embryo ◽  
Basement Membrane ◽  
Sem Images ◽  
Intimate Contact ◽  
Cellular Processes ◽  
Sem Study ◽  
Free Cells

In the chick embryo retina (days 3-4 of incubation), coinciding with an increase in cell death, specialized phagocytes characterized by intense acid phosphatase activity have been described. In these preparations, all free cells in the vitreal humor (vitreal cells) were strongly labeled. Conventional TEM and SEM techniques were used to characterize them and attempt to determine their relationship with retinal phagocytes.Two types of vitreal cells were distinguished. The first are located at some distance from the basement membrane of the neuroepithelium, and are rounded, with numerous vacuoles and thin cytoplasmic prolongations. Images of exo- and or endocytosis were frequent; the cells showed a well-developed Golgi apparatus (Fig. 1) In SEM images, the cells was covered with short cellular processes (Fig. 3). Cells lying parallel to or alongside the basement membrane are elongated. The plasma membrane is frequently in intimate contact with the basement membrane. These cells have generally a large cytoplasmic expansion (Fig. 5).

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