Development of intercellular junctions in the pulmonary epithelium of the foetal lamb

1978 ◽  
Vol 32 (1) ◽  
pp. 307-324
Author(s):  
E.E. Schneeberger ◽  
D.V. Walters ◽  
R.E. Olver
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cells ◽  
Tight Junctions ◽  
Lung Development ◽  
Light And Electron Microscopy ◽  
Intercellular Junctions ◽  
Intercellular Spaces ◽  
Thin Sections ◽  
Epithelial Tight Junctions ◽  
Foetal Lamb

The integrity of epithelial tight junctions in foetal mammalian lungs is essential to maintain the unique ionic composition of lung liquid, and to prevent leakage of serum proteins into peripheral air spaces. In the present study the development of intercellular junctions of the lining epithelium of foetal lamb lungs during gestation was examined by light and electron microscopy. Both thin sections and freeze-fracture replicas were examined by electron microscopy. By 39 days of gestation, epithelial tight junctions consist of a minimum of 3.1 +/− 1.6 (s.D.) and a maximum of 5.8 +/− 2.0 discontinuous rows of particles and short segments of strands on P face ridges and in complementary E face grooves, while from 58 to 76 days they are composed of a network of 4.3 +/− 1.6 to 7.7 +/− 1.9 focally interrupted P face strands. Complementary replicas show that many of the discontinuities on the P face are due to separation of junctional particles on to the E face during fracturing, and not to an absence of junctional particles. From 76 days to term, epithelial tight junctions (exclusive of upper airway epithelium which was not examined) resemble those of adult lungs, and consist of a continuous network of 4.5 +/− 2.0 to 7.5 +/− 2.5 P face strands and complementary particle-free grooves. Permeability measurements, published elsewhere, indicate that the epithelium is functionally ‘tight’ from 69 days onwards. Tight junctions in peripheral air-space epithelium, therefore, are structurally continuous and functionally ‘tight’ early in foetal lung development, and form seals at one end of long, narrow intercellular spaces; these features may be important for coupled ion and water transport. When the bounding epithelial cells become flattened, these narrow intercellular spaces remain intact as a result of complex interdigitations of adjacent cell membranes. Desmosomes were present throughout gestation near the abluminal side of the tight junctions and occasionally near the base of the intercellular space. These junctions may serve to connect cells to each other at a time when tight junctions may be mechanically weak. In addition, gap junctions are associated with tight junctions from the glandular through the canalicular stages of lung development. They disappear by 120 days when the epithelial cells are differentiated.

scholarly journals Immunocytochemical localization of actin in epithelial cells of rat small intestine by light and electron microscopy.

1988 ◽  
Vol 36 (7) ◽  
pp. 717-727 ◽  
Author(s):  
S J Hagen ◽  
J S Trier
Keyword(s):  
Electron Microscopy ◽  
Small Intestine ◽  
Epithelial Cells ◽  
Light And Electron Microscopy ◽  
Basal Membrane ◽  
Ground Substance ◽  
Structural Protein ◽  
Thin Sections ◽  
Filament Bundles ◽  
Lowicryl K4m

We used post-embedding immunocytochemical techniques and affinity-purified anti-actin antibody to evaluate localization of actin in epithelial cells of small intestine by fluorescence and electron microscopy. Small intestine was fixed with 2% formaldehyde-0.1% glutaraldehyde and embedded in Lowicryl K4M. One-micron or thin sections were stained with antibody followed by rhodamine- or colloidal gold-labeled goat anti-rabbit IgG, respectively. Label was present overlying microvilli, the apical terminal web, and the cytoplasm directly adjacent to occluding and intermediate junctions. Label was associated with outer mitochondrial membranes of all cells and the supranuclear Golgi region of goblet cells. Lateral cytoplasmic interdigitations between mature cells and subplasmalemmal filaments next to intrusive cells were densely labeled. The cytoplasm adjacent to unplicated domains of lateral membrane was focally labeled. Label was prominent over organized filament bundles within the subplasmalemmal web at the base of mature cells, whereas there was focal labeling of the cytoplasm adjacent to the basal membrane of undifferentiated cells. Basolateral epithelial cell processes were labeled. Label was focally present overlying the cellular ground substance. Our results demonstrate that actin is distributed in a distinctive fashion within intestinal epithelial cells. This distribution suggests that in addition to its function as a structural protein, actin may participate in regulation of epithelial tight junction permeability, in motile processes including migration of cells from the crypt to the villus tip, in accommodation of intrusive intraepithelial cells and in adhesion of cells to one another and to their substratum.

scholarly journals Effects of the cationic protein poly-L-arginine on airway epithelial cellsin vitro

2002 ◽  
Vol 11 (3) ◽  
pp. 141-148 ◽  
Author(s):  
Shahida Shahana ◽  
Caroline Kampf ◽  
Godfried M. Roomans
Keyword(s):  
Electron Microscopy ◽  
Epithelial Cells ◽  
Cell Membrane ◽  
Cell Damage ◽  
Membrane Damage ◽  
Light And Electron Microscopy ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Cationic Protein ◽  
Induced Apoptosis

Background: Allergic asthma is associated with an increased number of eosinophils in the airway wall. Eosinophils secrete cationic proteins, particularly major basic protein (MBP).Aim: To investigate the effect of synthetic cationic polypeptides such as poly-L-arginine, which can mimic the effect of MBP, on airway epithelial cells.Methods: Cultured airway epithelial cells were exposed to poly-L-arginine, and effects were determined by light and electron microscopy.Results: Poly-L-arginine induced apoptosis and necrosis. Transmission electron microscopy showed mitochondrial damage and changes in the nucleus. The tight junctions were damaged, as evidenced by penetration of lanthanum. Scanning electron microscopy showed a damaged cell membrane with many pores. Microanalysis showed a significant decrease in the cellular content of magnesium, phosphorus, sodium, potassium and chlorine, and an increase in calcium. Plakoglobin immunoreactivity in the cell membrane was decreased, indicating a decrease in the number of desmosomes.Conclusions: The results point to poly-L-arginine induced membrane damage, resulting in increased permeability, loss of cell-cell contacts and generalized cell damage.

The morphogenesis of avian tendon

1956 ◽  
Vol 144 (917) ◽  
pp. 556-572 ◽  
Keyword(s):  
Electron Microscopy ◽  
Average Diameter ◽  
Relative Volume ◽  
Morphological Features ◽  
Collagen Fibrils ◽  
Intercellular Spaces ◽  
Intercellular Substance ◽  
Thin Sections ◽  
Cellular Components ◽  
Development Proceeds

Observations by electron microscopy on thin sections of the metatarsal tendon of embryonic fowls show that in the 8-day embryo the earliest definable collagen fibrils of 80 Å in diameter are intimately associated with the cytoplasm of the compact, apparently syncytial, cells of which the tendon rudiment is composed. As development proceeds, some intracytoplasmic groups of fibrils are distinguishable, but intercellular spaces also develop and these gradually become filled with fibrils; finally, bundles are formed and lie packed between the adjacent cells. Soon the extracellular organization predominates until at 20days the average diameter of the fibrils is 400 Å and the normal 640 Å periodicity of collagen has been achieved. The morphological features demonstrated have been correlated with histochemical data, and the possible function of the various cellular components in the formation of the intercellular substance has been discussed. By the use of sections in which fibrils have been cut exactly transverse to the bundle axis it has been shown that each fibril is invested by interfibrillar material. As the diameter of the fibrils increases with age the relative volume of interfibrillar material within a bundle diminishes; it is therefore concluded that this material must contain either collagen or the necessary precursors in order to account for the enlargement of the fibrils. Thus the interfibrillar material is of fundamental importance to the formation and growth of the collagen fibrils.

Replication factories and nuclear bodies: the ultrastructural characterization of replication sites during the cell cycle

1994 ◽  
Vol 107 (8) ◽  
pp. 2191-2202 ◽  
Author(s):  
P. Hozak ◽  
D.A. Jackson ◽  
P.R. Cook
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
S Phase ◽  
Nuclear Bodies ◽  
Nuclear Antigen ◽  
Thin Sections ◽  
Permeabilized Cells ◽  
Ultrastructural Characterization ◽  
Replication Sites ◽  
Proliferating Cell

Sites of replication in synchronized HeLa cells were visualized by light and electron microscopy; cells were permeabilized and incubated with biotin-16-dUTP, and incorporation sites were immunolabelled. Electron microscopy of thick resinless sections from which approximately 90% chromatin had been removed showed that most DNA synthesis occurs in specific dense structures (replication factories) attached to a diffuse nucleoskeleton. These factories appear at the end of G1-phase and quickly become active; as S-phase progresses, they increase in size and decrease in number like sites of incorporation seen by light microscopy. Electron microscopy of conventional thin sections proved that these factories are a subset of nuclear bodies; they changed in the same characteristic way and contained DNA polymerase alpha and proliferating cell nuclear antigen. As replication factories can be observed and labelled in non-permeabilized cells, they cannot be aggregation artifacts. Some replication occurs outside factories at discrete sites on the diffuse skeleton; it becomes significant by mid S-phase and later becomes concentrated beneath the lamina.

Observations on the nephridial system of the cestode Moniezia expansa (Rud., 1805)

Parasitology ◽  
1969 ◽  
Vol 59 (2) ◽  
pp. 449-459 ◽  
Author(s):  
R. E. Howells
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Epithelial Cells ◽  
Connective Tissue ◽  
Intercellular Space ◽  
Technical Assistance ◽  
Light And Electron Microscopy ◽  
Flame Cell ◽  
Research Scholarship ◽  
Research Facilities

The nephridial system of M. expansa has been studied using light and electron microscopy, and a number of histochemical techniques have been used on sections of the worm. The organization of the nephridial system and the fine structure of the flame cells and the nephridial ducts are described. Pores, which connect the nephridial lumen to the intercellular space of the connective tissue, exist at the junction of a flame cell and a nephridial duct. These pores may be considered nephrostomes and the system therefore is not protonephridial as defined by Hyman (1951).The epithelium lining the nephridial ducts has a structure which suggests that it is metabolically active. It is postulated that the beating of the cilia of the flame cells draws fluid into the ducts via the nephrostomes, with absorption and/or secretion of solutes being carried out by the epithelial cells of the duct walls. The function of the nephridial system is discussed.I am grateful to Professor James Brough for the provision of research facilities at the Department of Zoology, University College, Cardiff, andtoDrD. A. Erasmus for much helpful advice during the course of the work. I wish to thank Professors W. Peters and T. Wilson for critically reading the manuscript and Miss M. Williams and Mr T. Davies for expert technical assistance.I also wish to thank the Veterinary Inspector and his staff at the Roath Abattoir, Cardiff, for their kind co-operation and assistance in obtaining material.The work was carried out under the tenure of an S.R.C. research scholarship.

scholarly journals MEMBRANE-COATING GRANULES OF KERATINIZING EPITHELIA

1965 ◽  
Vol 24 (2) ◽  
pp. 297-307 ◽  
Author(s):  
A. Gedeon Matoltsy ◽  
Paul F. Parakkal
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Epithelial Cells ◽  
Cell Envelope ◽  
Cell Periphery ◽  
Cell Surfaces ◽  
Intercellular Spaces ◽  
Cytoplasmic Granules ◽  
Coated Cell ◽  
Membrane Coating

The purpose of this study has been to obtain information on the development of the envelop of horny cells that resists the action of keratinolytic agents. Toward this end the epidermis, oral mucosa, and tongue epithelium of various vertebrates, as well as the isolated envelopes of horny cells, were examined by electron microscopy. It was found that small cytoplasmic granules (1,000 to 5,000 A) that develop within differentiating epithelial cells move toward the cell periphery, and after fusion with the plasma membrane, empty their contents into the intercellular spaces. The content of the granules spreads over the cell surfaces, and subsequently a thickened and coated cell envelope is formed that resists the action of keratinolytic agent. The membrane-coating granule is regarded as a specific differentiation product of the keratinizing epithelium. It contains numerous inner membranes and is assumed to engage in synthetic activities such as, perhaps, the formation of polysaccharides.

scholarly journals Disruption of Tight Junctions and Induction of Proinflammatory Cytokine Responses in Colonic Epithelial Cells by Campylobacter jejuni

2006 ◽  
Vol 74 (12) ◽  
pp. 6581-6589 ◽  
Author(s):  
Ming L. Chen ◽  
Zhongming Ge ◽  
James G. Fox ◽  
David B. Schauer
Keyword(s):  
Epithelial Cells ◽  
Tight Junctions ◽  
Campylobacter Jejuni ◽  
Transmembrane Protein ◽  
Intercellular Junctions ◽  
Subcellular Fractionation ◽  
Intestinal Epithelial ◽  
Intracellular Location ◽  
Mitogen Activated Protein ◽  
Triton X

ABSTRACT Campylobacter jejuni is a leading cause of human enterocolitis and is associated with postinfectious complications, including irritable bowel syndrome and Guillain-Barré syndrome. However, the pathogenesis of C. jejuni infection remains poorly understood. Paracellular pathways in intestinal epithelial cells are gated by intercellular junctions (tight junctions and adherens junctions), providing a functional barrier between luminal microbes and host immune cells in the lamina propria. Here we describe alterations in tight junctions in intestinal epithelial monolayers following C. jejuni infection. Apical infection of polarized T84 monolayers caused a time-dependent decrease in transepithelial electrical resistance (TER). Immunofluorescence microscopy revealed a redistribution of the tight junctional transmembrane protein occludin from an intercellular to an intracellular location. Subcellular fractionation using equilibrium sucrose density gradients demonstrated decreased hyperphosphorylated occludin in lipid rafts, Triton X-100-soluble fractions, and the Triton X-100-insoluble pellet following apical infection. Apical infection with C. jejuni also caused rapid activation of NF-κB and AP-1, phosphorylation of extracellular signal-regulated kinase, Jun N-terminal protein kinase, and p38 mitogen-activated protein kinases, and basolateral secretion of the CXC chemokine interleukin-8 (IL-8). Basolateral infection with C. jejuni caused a more rapid decrease in TER, comparable redistribution of tight-junction proteins, and secretion of more IL-8 than that seen with apical infection. These results suggest that compromised barrier function and increased chemokine expression contribute to the pathogenesis of C. jejuni-induced enterocolitis.

scholarly journals The Fine Structure of the Wheat Scutellum During Germination

1972 ◽  
Vol 25 (3) ◽  
pp. 469 ◽  
Author(s):  
JG Swift ◽  
TP O'brien
Keyword(s):  
Electron Microscopy ◽  
Fine Structure ◽  
Epithelial Cells ◽  
Light And Electron Microscopy ◽  
Cell Types ◽  
Wall Material ◽  
Cytological Evidence ◽  
Starch Grains ◽  
Parenchyma Cells ◽  
Cytological Changes

The cytological changes that take place in the scutellar epithelium and parenchyma during the first 5 days of germination are described by light and electron microscopy. Within 6 hr small starch grains appear in the plastids of both cell types and the size and number of starch grains increase gradually as germination proceeds. Later in germination starch disappears again from the plastids in the epithelial cells, but large starch grains still remain in the parenchyma cells. The reserves of the protein bodies are hydrolysed and the residual vacuoles undergo extensive coales-cence. Modifications in the appearance of the wall material of the epithelial cells as these cells elongate are illustrated and possible functional bases for these changes are suggested. The cells of the scutellar epithelium show no cytological evidence for their known functions of diastase secretion and nutrient absorption.

Vascular permeability to particulate fat: morphological observations on vessels of lactating mammary gland and of lung

1968 ◽  
Vol 169 (1015) ◽  
pp. 153-165 ◽  
Keyword(s):  
Electron Microscopy ◽  
Mammary Gland ◽  
Light And Electron Microscopy ◽  
Intercellular Junctions ◽  
Multivesicular Bodies ◽  
Intravenous Injections ◽  
Lactating Mammary Gland ◽  
Fat Particles ◽  
Freely Suspended ◽  
Pinocytic Vesicles

Small blood vessels of the lactating mammary gland and of the lung in rats, mice and guinea-pigs were examined after feeding fat or after the intravenous injections of chyle or an artificial fat emulsion. In both tissues the vessels are lined by a continuous endothelium and basement membrane. By electron microscopy, chylomicra and particles of the artificial emulsion could be seen in the vessel lumen, but not in pinocytic vesicles and intercellular junctions, nor on the outer surface of the endothelium. The chylomicra and artificial particles were more numerous in vessels in the mammary gland than in the lung. In the mammary gland they were concentrated against the luminal surface of the endothelium and appeared to adhere closely to it. Both types of particle behaved similarly except that the artificial particles were seen rather more frequently within endothelial vacuoles or multivesicular bodies. In the lung, chylomicra and artificial particles were freely suspended in the blood plasma. The action of an enzyme, believed to be clearing factor lipase, on chylomicra and artificial fat particles in the mammary vessels could be demonstrated histochemically by light and electron microscopy. The possible relation of this enzyme to the close adhesion of fat particles to the endothelium and its role in the transport of fat through the vessel wall is discussed.

Sign in / Sign up

Export Citation Format

Share Document