scholarly journals CELL JUNCTIONS IN AMPHIBIAN SKIN

1965 ◽  
Vol 26 (1) ◽  
pp. 263-291 ◽  
Author(s):  
Marilyn G. Farquhar ◽  
George E. Palade
Keyword(s):  
Stratum Corneum ◽  
Membrane Fusion ◽  
Water Soluble ◽  
Cell Junctions ◽  
Physiological Data ◽  
Junctional Complex ◽  
Stratum Granulosum ◽  
Intercellular Spaces ◽  
Outermost Layer ◽  
Zonulae Occludentes

Cell junctions have been investigated in the amphibian epidermis, a stratified squamous epithelium, and compared to those described previously in simple columnar epithelia of mammalian cavitary organs. In adult frogs and toads, and in larvae approaching metamorphosis, belts of membrane fusion or zonulae occludentes of considerable depth are regularly found between adjoining cells of the outermost layer of the stratum corneum, binding the cells together into a continuous, uninterrupted sheet. Another set of occluding zonules appears in the second cornified layer (when such a layer is present), and a third set usually occurs in the outermost layer of the stratum granulosum. Specialized elements described as "modified" and "composite" desmosomes are encountered along the lateral and basal aspects, respectively, of the cornified cells; ordinary desmosomes and maculae occludentes (i.e., spots of membrane fusion) are found in all other strata. The usual 200 A intercellular gap is generally maintained between the cells of the stratum germinativum at the basal ends of the intercellular spaces. Hence, the intercellular spaces of the epidermis form a largely continuous network, closed to the external medium and open to the dermal interstitia. The situation is comparable to that found in columnar epithelia, except that the intercellular spaces are much more extensive, and an extracellular subcompartment (or two) apparently exists in the stratum corneum and between the latter and the stratum granulosum. The last subcompartment is usually filled with a dense substance, probably derived from discharged secretory granules. The tripartite junctional complex characteristic of lumen-lining epithelia (i.e., a zonula occludens followed by a zonula adhaerens, and desmosome) is seen only in early larvae; in adults and in larvae approaching metamorphosis, the occluding zonule is followed directly by a series of modified desmosomes. Interpreted in the light of current physiological data, these findings suggest that the diffusion of water, ions, and small, water-soluble molecules is impeded along the intercellular spaces of the epidermis by zonulae occludentes while it is facilitated from cell to cell within the epidermis by zonulae and maculae occludentes.

scholarly journals The permeability barrier in mammalian epidermis.

1975 ◽  
Vol 65 (1) ◽  
pp. 180-191 ◽  
Author(s):  
P M Elias ◽  
D S Friend
Keyword(s):  
Plasma Membrane ◽  
Stratum Corneum ◽  
Freeze Fracture ◽  
Freeze Substitution ◽  
Water Soluble ◽  
Structural Basis ◽  
Fracture Plane ◽  
Permeability Barrier ◽  
Stratum Granulosum ◽  
Lamellar Bodies

The structural basis of the permeability barrier in mammalian epidermis was examined by tracer and freeze-fracture techniques. Water-soluble tracers (horesradish peroxidase, lanthanum, ferritin) were injected into neonatal mice or into isolated upper epidermal sheets obtained with staphylococcal exfoliatin. Tracers percolated through the intercellular spaces to the upper stratum granulosum, where further egress was impeded by extruded contents of lamellar bodies. The lamellar contents initially remain segregated in pockets, then fuse to form broad sheets which fill intercellular regions of the stratum corneum, obscuring the outer leaflet of the plasma membrane. These striated intercellular regions are interrupted by periodic bulbous dilatations. When adequately preserved, the interstices of the stratum corneum are wider, by a factor of 5-10 times that previously appreciated. Freeze-fracture replicas of granular cell membranes revealed desmosomes, sparse plasma membrane particles, and accumulating intercellular lamellae, but no tight junctions. Fractured stratum corneum displayed large, smooth, multilaminated fracture faces. By freeze-substitution, proof was obtained that the fracture plane had diverted from the usual intramembranous route in the stratum granulosum to the intercellular space in the stratum corneum. We conclude that: (a) the primary barrier to water loss is formed in the stratum granulosum and is subserved by intercellular deposition of lamellar bodies, rather than occluding zonules; (b) a novel, intercellular freeze-fracture plane occurs within the stratum corneum; (c) intercellular regions of the stratum corneum comprise an expanded, structurally complex, presumably lipid-rich region which may play an important role in percutaneous transport.

Tight junction dysfunction in the stratum granulosum leads to aberrant stratum corneum barrier function in claudin-1-deficient mice

2013 ◽  
Vol 70 (1) ◽  
pp. 12-18 ◽  
Author(s):  
Tomoko Sugawara ◽  
Noriko Iwamoto ◽  
Masaya Akashi ◽  
Taro Kojima ◽  
Junzo Hisatsune ◽  
...  
Keyword(s):  
Tight Junction ◽  
Stratum Corneum ◽  
Barrier Function ◽  
Stratum Granulosum ◽  
Deficient Mice

Human Skin Binding and Absorption of Contaminants from Ground and Surface Water During Swimming and Bathing

1989 ◽  
Vol 8 (5) ◽  
pp. 853-859 ◽  
Author(s):  
Ronald C. Wester ◽  
Howard I. Maibach
Keyword(s):  
Surface Water ◽  
Stratum Corneum ◽  
Human Skin ◽  
The Body ◽  
Water Soluble ◽  
Exposure Effect ◽  
Human Stratum Corneum ◽  
Water Dilution

Contaminants exist in ground and surface water. Human skin has the capacity to bind and then absorb these contaminants into the body during swimming and bathing. Powdered human stratum corneum will bind both lipid-soluble (alachlor, polychlorinated biphenyls [PCBs], benzene) and water-soluble (nitroaniline) chemicals. In vitro (human skin) and in vivo (Rhesus monkey) studies show that these chemicals readily distribute into skin, and then some of the chemical is absorbed into the body. Linearity in binding and absorption exists for nitroaniline over a 10-fold concentration range. Multiple exposure to benzene is at least cumulative. Binding and absorption can be significant for exposures as short as 30 min, and will increase with time. Absorption with water dilution increased for alachlor, but not for dinoseb. Soap reversed the partitioning of alachlor between human stratum corneum and water. The PCBs could be removed from skin by soap and water (70% efficiency) for up to 3 h and then decontamination potential decreased, due to continuing skin absorption. The model in vitro and in vivo systems used should permit easy estimation of this area of extensive human exposure effect on risk assessment.

Functional organization of the bovine rumen epithelium

2005 ◽  
Vol 288 (1) ◽  
pp. R173-R181 ◽  
Author(s):  
C. Graham ◽  
N. L. Simmons
Keyword(s):  
Plasma Membrane ◽  
Gap Junctions ◽  
Stratum Corneum ◽  
Connexin 43 ◽  
Functional Organization ◽  
Stratum Granulosum ◽  
Bovine Rumen ◽  
Rumen Epithelium ◽  
Stratum Spinosum ◽  
Cell Layers

The functional organization of the bovine rumen epithelium has been examined by electron and light microscopy combined with immunocytochemistry to define a transport model for this epithelium. Expression of connexin 43, an integral component of gap junctions, the tight-junction molecules claudin-1 and zonula occludens 1 (ZO-1), and the catalytic α-subunit of Na+-K+-ATPase was demonstrated by SDS-PAGE and Western blotting. From the lumen surface, four cell layers can be distinguished: the stratum corneum, the stratum granulosum, the stratum spinosum, and the stratum basale. Both claudin-1 and ZO-1 immunostaining showed plasma membrane staining, which was present at the stratum granulosum with decreasing intensity through the stratum spinosum to the stratum basale. The stratum corneum was negative for claudin-1 immunostaining. Transmission electron microscopy confirmed that occluding tight junctions were present at the stratum granulosum. Plasma membrane connexin 43 immunostaining was most intense at the stratum granulosum and decreased in intensity through stratum spinosum and stratum basale. There was intense immunostaining of the stratum basale for Na+-K+-ATPase, with weak staining of the stratum spinosum. Both the stratum granulosum and the stratum corneum were essentially negative. Stratum basale cells also displayed a high mitochondrial density relative to more apical cell layers. We conclude that epithelial barrier function may be attributed to the stratum granulosum and that cell-cell gap junctions allow diffusion to interconnect the barrier cell layer with the stratum basale where Na+-K+-ATPase is concentrated.

Horseradish Peroxidase Permeation from the Capillaries of the Stria Vascularis after Inoculation of Endotoxin into the Middle Ear

1997 ◽  
Vol 106 (5) ◽  
pp. 394-398 ◽  
Author(s):  
Kensuke Watanabe ◽  
Yasuo Tanaka
Keyword(s):  
Horseradish Peroxidase ◽  
Middle Ear ◽  
Stria Vascularis ◽  
Femoral Vein ◽  
Cell Junctions ◽  
Intercellular Spaces ◽  
Basal Turn ◽  
Pinocytotic Vesicles ◽  
Marginal Cells ◽  
Intermediate Cells

Escherichia coli-derived endotoxin was inoculated in the middle ear of guinea pigs 24 hours after being injected intraperitoneally. Twenty-four hours after the middle ear inoculation, horseradish peroxidase (HRP) was injected via the femoral vein and the permeability of HRP through the capillaries of the stria vascularis and the destination of the leaked HRP were examined. A large amount of HRP leaked out of the capillary through the opened endothelial cell junctions and penetrated the enlarged intercellular spaces. Leaked HRP entered the pinocytotic vesicles of the intermediate cells. Even slightly degenerated intermediate cells retained this function. The HRP penetrated the spongelike structure of the marginal cells leading to the intercellular space. This structure was not observed without endotoxin. The HRP could not pass to the cochlear duct through the tight junctions between marginal cells. Blood sludging was observed in the strial capillaries. It appeared more frequently in the upper three turns than in the basal turn. The HRP leakage out of the capillaries was observed not only in the upper three turns but also in the basal turn.

BLOOD–TESTIS BARRIER: EVIDENCE FOR INTACT INTER-SERTOLI CELL JUNCTIONS AFTER HYPOPHYSECTOMY IN THE ADULT RAT

1978 ◽  
Vol 76 (1) ◽  
pp. 87-91 ◽  
Author(s):  
L. HAGENÄS ◽  
L. PLÖEN ◽  
H. EKWALL
Keyword(s):  
Sertoli Cell ◽  
Structural Integrity ◽  
Cell Junctions ◽  
Junctional Complex ◽  
Tracer Technique ◽  
Adult Rats ◽  
Adult Rat ◽  
Hormonal Dependence ◽  
Lanthanum Tracer ◽  
Blood Testis Barrier

SUMMARY To study the hormonal dependence of the blood–testis barrier, adult rats were hypophysectomized and the ultrastructural integrity of the inter-Sertoli cell junctional complex was examined at various times with a lanthanum tracer technique. It was found that the structural integrity of the inter-Sertoli cell junctions and their capacity to exclude lanthanum from the adluminal compartment were preserved up to 35 days after hypophysectomy. Furthermore, transport of newly formed spermatocytes through the inter-Sertoli cell junctions still occurred 20 days after hypophysectomy. It is therefore concluded that the function of the inter-Sertoli cell junctional complex is not directly dependent on gonadotrophic or androgenic hormones, but is regulated by other mechanisms.

Role of Surfactant in Peritoneal Dialysis

2000 ◽  
Vol 20 (5) ◽  
pp. 503-515 ◽  
Author(s):  
Brian A. Hills
Keyword(s):  
Peritoneal Dialysis ◽  
Water Solubility ◽  
Adhesion Formation ◽  
Mesothelial Cell ◽  
Water Soluble ◽  
Cell Junctions ◽  
Pathogen Invasion ◽  
Water Transmission ◽  
Future Direction

Evidence is reviewed that demonstrates how the mesothelial cell in the normal peritoneum and comparable serosal cavities secretes surface-active phospholipid (SAPL) as a means of protecting itself and the membrane it forms with its neighbors. It is shown how SAPL, if adsorbed (reversibly bound) to mesothelium, can impart excellent lubricity, antiwear and release (antistick) properties, while impeding surgical adhesion formation. More-speculative benefits include acting as a deterrent to fibrosis and as a barrier to both protein leakage and pathogen invasion by spanning cell junctions. Such spanning would also “pin down” cell corners, impeding peeling as the first step in exfoliation encountered in prolonged continuous ambulatory peritoneal dialysis (CAPD). The molecular mechanism underlying each of these possible functions is adsorption. Morphological and hydrophobicity studies are discussed as validation for such an adsorbed lining and how it can be fortified by administering exogenous SAPL. Any role for SAPL in ultrafiltration is much more controversial. However, a surfactant lining can explain the very high permeability of the membrane to lipid-soluble drugs, implying that it is a barrier to water-soluble solutes. The clinical and animal evidence is conflicting but would seem to be best explained by a role for the barrier in promoting semipermeability, and hence the osmotic driving force for water transmission. Thus, adsorption of exogenous SAPL in CAPD patients with low ultrafiltration seems to restore this barrier function. The future direction for surfactant in CAPD would seem to rest with the physical chemists in producing formulations that optimize adsorption, probably involving a compromise between water solubility and surface activity of the phospholipids selected. It might even warrant using the interdialytic interval for re-adsorbing SAPL without the problem of dilution by a large volume of dialysate.

Plasma membranes, cell junctions and cuticle of the rectal chloride epithelia of the larval dragonfly Aeshna cyanea

1983 ◽  
Vol 59 (1) ◽  
pp. 159-182
Author(s):  
J. Kukulies ◽  
H. Komnick
Keyword(s):  
Gap Junctions ◽  
Structural Control ◽  
Plasma Membranes ◽  
Freeze Fracture ◽  
Septate Junction ◽  
Cell Junctions ◽  
Junctional Complex ◽  
Apical Region ◽  
Thin Sections ◽  
Aeshna Cyanea

The cell membranes and cell junctions of the rectal chloride epithelia of the larval dragonfly Aeshna cyanea were examined in thin sections and by freeze-fracture. These epithelia function in active ion absorption and maintain a high concentration gradient between the haemolymph and the fresh-water environment. Freeze-fracturing reveals fine-structural differences in the intramembraneous particles of the luminal and contraluminal plasma membranes of these epithelia, reflecting the functional diversity of the two membranes, which are separated by the junctional complex. The particle frequency of the basolateral plasma membranes is reduced after transfer of the larvae into high concentrations of environmental salinity. The junctional complex is located in the apical region and composed of three types of cell junctions: the zonula adhaerens, seen in freeze-fracture as a nearly particle-free zone; the extended and highly convoluted pleated septate junction and randomly interspersed gap junctions of the inverted type. Gap junctions also occur between the basolateral plasma membranes. They provide short-cuts in the diffusion pathway for direct and rapid co-ordination of the interconnected cell processes. Colloidal and ionic lanthanum tracer solutions applied in vivo from the luminal side penetrate through the cuticle via epicuticular depressions, but invade only the apical portion of the junctional complex. This indicates that the pleated septate junction constitutes a structural control of the paracellular pathway across the chloride epithelia, which are devoid of tight junctions. The structure of the pleated septate junctions is interpreted as a device for the extension of the diffusion distance, which is inversely related to the net diffusion. A conservative estimate of the total length of the junction, and the number and extension of septa reveals that the paracellular route exceeds the transcellular route by a factor of 50.

scholarly journals FSH regulates the formation of adherens junctions and ectoplasmic specialisations between rat Sertoli cells in vitro and in vivo

2006 ◽  
Vol 189 (2) ◽  
pp. 381-395 ◽  
Author(s):  
P Sluka ◽  
L O’Donnell ◽  
J R Bartles ◽  
P G Stanton
Keyword(s):  
Sertoli Cell ◽  
Sertoli Cells ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Junctional Complex ◽  
Intermediate Filament Protein ◽  
Adult Rat

Spermatogenesis is dependent on the ability of Sertoli cells to form mature junctions that maintain a unique environment within the seminiferous epithelium. Adjacent Sertoli cells form a junctional complex that includes classical adherens junctions and testis-specific ectoplasmic specialisations (ES). The regulation of inter-Sertoli cell junctions by the two main endocrine regulators of spermatogenesis, FSH and testosterone, is unclear. This study aimed to investigate the effects of FSH and testosterone on inter-Sertoli cell adherens junctions (as determined by immunolocalisation of cadherin, catenin and actin) and ES junctions (as determined by immunolocalisation of espin, actin and vinculin) in cultured immature Sertoli cells and GnRH-immunised adult rat testes given FSH or testosterone replacement in vivo. When hormones were absent in vitro, adherens junctions formed as discrete puncta between interdigitating, finger-like projections of Sertoli cells, but ES junctions were not present. The adherens junction puncta included actin filaments that were oriented perpendicularly to the Sertoli cell plasma membrane, but were not associated with the intermediate filament protein vimentin. When FSH was added in vitro, ES junctions formed, and adjacent adherens junction puncta fused into extensive adherens junction belts. After hormone suppression in vivo, ES junctions were absent, while FSH replacement restored ES junctions, as confirmed by electron microscopy and confocal analysis of ES-associated proteins. Testosterone alone did not affect adherens junctions or ES in vitro or in vivo. We conclude that FSH can regulate the formation of ES junctions and stimulate the organisation and orientation of extensive adherens junctions in Sertoli cells.

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