Intercellular Attachments Research Articles

Evidence for the presence of actin‐associated intercellular adhesion junctions between interstitial cells of Leydig in the ground squirrel testis

Interstitial cells of Leydig characteristically occur in clusters around blood vessels. Often these clusters remain intact when interstitial tissues are mechanically separated from other components of the testis. The presence of strong intercellular attachments is most likely one of the factors responsible for maintaining the integrity of Leydig cell clusters. In many tissues, actin associated adhesion junctions commonly provide intercellular attachment. To determine if actin associated adhesion junctions are present between Leydig cells, we have used 1) immunofluorescence to probe for two components that characterize these junctions in other tissues and 2) electron microscopy to examine areas of intercellular contact for evidence of microfilament related adhesion junctions. Isolated clusters of unsectioned cells, which had been fixed and detergent extracted, were probed with the F-actin specific strains rhodamine phalloidin and NBD-phallacidin and with an affinity purified primary antibody raised against human platelet vinculin. In regions of intercellular contact, fluorescence staining with the actin probes was intense and appeared as a solid linear band. Similar regions also stained with the vinculin probe. In double label experiments, actin and vinculin probes were co-distributed at sites of intercellular contact. Zones of intercellular contact, apparently similar to those detected with fluorescence microscopy, were observed at the ultrastructural level. At these sites, subsurface filaments, interpreted by us as actin, formed a dense carpet adjacent to the plasma membrane on each side of the junction. These filaments appeared to be organized into networks rather than discrete bundles.(ABSTRACT TRUNCATED AT 250 WORDS)

Lymphocytic periductulitis of the human testicular efferent ductules: evidence of an autoimmune disorder.

The transport system of sperm in the testis and epididymis was studied histologically on samples randomly collected at autopsy from 253 patients, none of whom had evidence of generalized infection or autoimmune disease. Focal lymphocytic periductulitis of the efferent ductules was found in 50% of patients aged 30-39 years and in 44% of patients aged 20-29 years. No similar lesion was observed in other regions of the transport system such as straight tubules, rete testis, and epididymis. Periductular fibrosis or hyalinosis attributed to inflammation increased with age and was present in 90% of patients aged 80-89 years. These results suggest that an autoimmune inflammatory reaction against leaked intraductular autoantigens may occur through the vulnerable barrier of intercellular junctional attachments in the efferent ductules.

Interleukin 6 decreases cell-cell association and increases motility of ductal breast carcinoma cells.

Treatment of transformed breast duct epithelial cells with IL-6 produces a unique cellular phenotype characterized by diminished proliferation and increased motility. Human ductal carcinoma cells (T-47D and ZR-75-1 lines) are typically epithelioid in shape and form compact colonies in culture. Time-lapse cinemicrography shows that some untreated cells can transiently become fusiform or stellate in shape and separate from each other within a colony, but they usually rejoin their neighbors. While IL-6 suppresses the proliferation of these carcinoma cells, the IL-6-treated cells generally become stellate or fusiform and show increased motility. These changes persist as long as the cells are exposed to IL-6. This results in the dispersal of cells within colonies. The effects on cell growth, shape, and motility are reversible upon removal of IL-6. IL-6-treated T-47D cells display diminished adherens-type cell junctions, as indicated by markedly decreased vinculin-containing adhesions and intercellular desmosomal attachments. The effects on ZR-75-1 cell shape, colony number, and DNA synthesis are dependent on IL-6 concentration in the range from 0.15 to 15 ng/ml. Higher concentrations are required in T-47D cells for equivalent effects. Anti-IL-6 immune serum blocks IL-6 action. IL-6 represents a well-characterized molecule that regulates both the proliferation and junction-forming ability of breast ductal carcinoma cells.

ヒト歯肉部培養上皮細胞のケラチン中間線維およびデスモゾームの分布に対する天ぽうそう患者血清の影響

Pemphigus vulgaris is characterized by suprabasal splitting of the epithelium and loss of intercellular attachments. In order to clarify the molecular mechanism of blister formation in oral mucosa in pemphigus vulgaris, we further analyzed the effects of pemphigus serum on the distribution of keratin intermediate filaments and also on that of desmoplakin I, II which is one of the components of desmosome, major attachment apparatus between keratinocytes. After incubation with pemphigus serum for 96 hrs at 37°C, we observed a dotted structure around the nucleus using anti-keratin monoclonal antibodies (PKK1, PKK2, PKK3 and anti-cytokeratin pan) in some of the cells from normal gingiva, and some decrease in fibrous radiating structures as we previously reported. All of anti-keratin monoclonal antibodies we used stained this dotted structure, although PKK2 stained most clearly them as well as fibrous structure among antibodies. Similar dotted staining was also observed when antidesmoplakin I, H monoclonal antibody was applied.These results suggest that the binding of pemphigus antibody to keratinocyte membrane induced the structural changes in keratin intermediate filaments, also in desmosomes, and a complex of them. We consider that these phenomena might be a characteristic feature of oral keratinocytes.

Isolation and characterization of a spontaneously arising long-lived line of human keratinocytes (NM1)

The long-lived keratinocyte line, NM 1, was isolated from the epidermis of a pool of foreskins obtained from apparently normal neonates at the time of circumcision. Cultures were initiated in Dulbecco's minimal essential medium containing 20% fetal bovine serum, 0.4 micrograms/ml hydrocortisone, 10(-9) M cholera toxin, and 10 ng/ml epidermal growth factor using mitomycin C-treated 3T3 cells as a feeder layer. Unlike normal keratinocytes which survive for only 150 generations these cells have been in culture for more than a year and have been carried for more than 400 doublings. The cells seem to follow a pathway of growth and differentiation that is very similar to normal keratinocytes. Cytokeratin fibrils, intercellular attachments, and cornified envelopes were observed. The keratin polypeptides isolated from the NM 1 cells were similar to those previously described in normal cultured cells; the presence of profilaggrin and involucrin was demonstrated by sodium dodecyl sulfate electrophoresis and immunoblotting with monoclonal antibodies specific to these proteins. The NM 1 cells showed a reduced dependency on 3T3 feeder cells but did not form tumors when placed into athymic nude mice. Screening of the cells for SV40, BK, HPV 16, and HPV 18 viruses was negative. The NM 1 cells showed trisomy of chromosome 8. The long-lived nature of these cells makes them a valuable model for studying growth and differentiation of keratinocytes.

Effects of synthetic blood and crystalloid cardioplegic solutions on coronary endothelium: An experimental scanning electron microscope study

In an experimental study the effects of Fluosol DA (added with potassium chloride) on the vascular interface and endothelial cells were compared to those of crystalloid potassium cardioplegic solution using scanning electron microscope. Twenty rabbits (10 in each group) were sacrificed, the hearts with ascending aorta were immediately excised, and cold oxygenated solution was infused via a cannula inserted into the cross-clamped aorta. The hearts were left immersed in the perfusion medium for 2 hr. In the Fluosol DA group endothelial cover and endothelial cells were normal or minimal changes were seen in seven cases. Occasional breaking of intercellular attachments, small areas of denuded flow surface, and disappearance of microvilli were seen in three cases. In the crystalloid potassium cardioplegic group 7 of the 10 cases showed moderate or severe damage with large areas of denuded flow surface. The present experimental protocol represented an extreme situation where no collateral coronary blood was present. The coronary endothelial damage was obvious after the crystalloid potassium cardioplegic solution. Similar damage was not found following Fluosol DA infusion.

A quantitative study of structural features, synapses and nearest-neighbour relationships of small, granule-containing cells in the rat superior cervical sympathetic ganglion at various adult stages

Groups and sub-groups (clusters) of small granule-containing cells (“small cells”) were analysed at 3 and 6μm intervals and in serial sections, in rats aged 2–13 months. Fully intraganglionic clusters of small cells were all found to receive an incoming (“afferent”) innervation, of the order of 3–6 afferent terminals per cell, derived from axons of preganglionic type via multifocal. symmetrical, mainly axosomatic synapses. No evidence was obtained of sharing of preganglionic inputs between small cells and principal neurones. Intraganglionic clusters also regularly gave outgoing (“efferent”) synapses of the asymmetrical type, of the order of 2–6 per cell, to intraganglionic nerve elements; 30–50% of these synapses were given from somata, 50–70% from processes of the small cells. Whenever the postsynaptic structure was identifiable these synapses were all found to be given to postganglionic neurones or their dendrites, principally to spine-like processes or slender twigs. In some ganglia a few efferent synapses to other small cells were observed; these were of the symmetrical type. Efferent synapses to nerve profiles resembling chemosensory axon terminals, also of the symmetrical type, were extremely infrequent (fewer than 1% of all efferent synapses) in intraganglionic small cell groups and appeared virtually restricted to glomus-like clusters of small cell, which lay intracapsularly, or in and near the bases of nerves entering or leaving the ganglion. Almost all groups and clusters of small cells were located near to fenestrated capillary vessels, which are not found elsewhere in the ganglion. The implications of possible non-synaptic release of material from small cells via membrane regions not covered by satellite cell cytoplasm, were explored in a nearest-neighbour analysis. These “exposed” regions comprised 1–3% of the small cell surface, a proportion comparable with those engaged in receiving afferent synapses or in giving efferent synapses. The majority of such regions faced toward other nerve profiles (axons and dendrites) ensheathed in satellite cytoplasm (mean, 30%), intraganglionic tissue spaces wider than 3 μm (mean, 30%) or other small cells (mean, 14%); 25% faced toward blood vessels, but of these vascularly directed regions, only one fifth (or 5% of the total) on average faced directly toward fenestrated endothelium, the rest being non-fenestrated and/or separated by pericyte processes from the exposed regions of small cell membrane. Thirty-three percent of the small cells in a sample of 242 lay within 2μm of the nearest blood vessel. Thus the vascular relationship is close, but vascular fenestrations would not appear to provide the major or most direct route for the distribution of secretions from the small cells. Serial section analyses showed variation between small cells within a cluster and also between clusters in the extent of their synaptic and other relationships: some small cells lacked exposed membrane, some gave no efferent synapses, whereas others exhibited both features simultaneously. In older rats (up to 13 months) the afferent synaptic terminals upon the small cells were larger and gave more synaptic foci, though the terminals themselves were not more numerous; points of efferent synapse from the small cells increased in incidence; processes of the small cells increased in volume and incidence; and there was evidence of increasing separation of small cells, with a shift of intercellular attachments from the somata out on to the processes. The proportion and distribution of regions of exposed membrane remained relatively constant. The cytoplasmic volume of the small cells was found to vary according to the incidence of afferent synaptic terminals and to the weight of the rat. These findings are discussed in relation to the possible actions of the small cells. It is concluded that the small granule-containing cells in this ganglion of the rat are consistently both interneurone- and paraneurone-like, exerting a focused synaptic influence upon the principal neurones in addition to a more diffuse non-synaptic influence which may include both preganglionic axons and postganglionic neurones, as well as other small cells and the ganglionic vasculature. Physiological and pharmacological evidence suggests that their effects on ganglionic transmission may be directly inhibitory or indirectly facilitatory, or both; the present observations suggest that these effects can be precisely recruited, possibly differentially from principal neurone activation, and may be directed to selected pathways through the ganglion.

Physical Analysis of Tissue Mechanics in Amphibian Gastrulation

During morphogenesis, intercellular attachments constrain cell mobility so that embryonic tissues may (i) deform as solid sheets of tightly bound cells, (ii) disperse to migrate as separate cells or (iii) flow as multicellular liquids (in which cells remain aggregated yet can still slide past one another). By modelling deep germ layers as multicellular liquids in amphibian gastrulation, Davis and I have predicted, and then confirmed experimentally, (i) the area-invariance of deep-germ-layer surface tensions in vitro , (ii) spontaneous cell slippage in deformed deep—germ—layer cell aggregates and (iii) correlations of tissue surface tensions with tissue positioning in deep-germ-layer cell-sorting and aggregate—fusion experiments. Liquid—tissue flow involves intercalations of interior cells into expanding tissue interfaces (or withdrawal of surface cells from shrinking tissue interfaces). Tissue surface tensions are macroscopic reflections of the microscopic, tissue—specific adhesive differentials which direct these cell translocations. Such adhesive differentials may act independently of, or together with, active cell—shape changes, chemotaxis, contact guidance and/or haptotaxis in controlling embryonic tissue rearrangements. Deep cell intercalations in vivo occur throughout amphibian gastrulation: during ectodermal epiboly; during marginal—zone extension and convergence (and therefore blastopore closure); during mesodermal involution; and probably during the anterior spreading and axial extension (and therefore dorsal convergence) of involuted mesoderm. Tissue—surface—tension measurements may help determine (i) which of these cell—intercalation processes are active and which are passive, (ii) the specific contributions of various microscopic cell properties to the regulation of liquid—like germ—layer assembly and (iii) similarities and differences between in vitro and in vivo control mechanisms governing amphibian gastrulation.

A cellular reticulum of fibroblast-like cells in the rat intestine: scanning and transmission electron microscopy.

Fibroblast-like cells of the rat intestinal villi were studied by scanning and transmission electron microscopy. They were observed to be flattened and stellate in shape and had many slender processes. By means of intercellular attachments, the cells formed a network covering the microvascular tree of the villous core. Their cytoplasmic features essentially resembled those of fibroblasts. It is suggested that this three-dimensional network of fibroblast-like cells might act as a skeleton for the villi and also influence the efficiency of absorption and transportation of nutrients by its contraction.

Treatment of Darier´s disease with an oral aromatic retinoid (Ro 10-9359): a clinical and light and electron microscopic study

An aromatic retinoid (Ro 10-9359) cleared 6 of 8 patients with Darier´s disease in 4-6 weeks. After discontinuing the treatment, remission was maintained for up to 5 months. In 2 severe cases continuous treatment proved necessary in order to maintain the improved state. Acantholysis, various types of dyskeratosis and acanthosis with downward proliferation of rete ridges were seen by light microscopy before treatment. Electron microscopy revealed a decreased number of desmosomes and other cellular attachments and conspicuous microvillous changes of cell surface in separated basal cells. Keratinization in epidermal cells was premature and characterized by abnormal aggregations of keratinization products. Under the influence of retinoid there seemed to appear a new generation of basal cells better able to form intercellular attachments, after which the progress of keratinization in the entire epidermis shifted towards normal, and acanthosis decreased.

Electron microscopy in surgical pathology: a selective review

The high resolution provided by electron microscopy can contribute to histomorphological diagnosis by allowing the detection of structures which are invisible to the light microscope. These structures include characteristic nuclear or cytoplasmic contours, intercellular attachments and intracellular components. The recognition of such features may allow specific diagnosis in lesions which cannot be precisely categorized by light microscopy. Electron microscopy is particularly useful for the diagnosis of neoplasms. This review describes some of the characteristic morphological features which can be demonstrated in neoplastic cells by electron microscopy and briefly considers several areas where the technique is of special value. Electron microscopy is now an integral part of the diagnostic process in surgical pathology and can be regarded as a routine technique rather than a special procedure to be delegated to others.

Transitory cell attachments in the differentiating glomerular epithelium of the opossum metanephros

Numerous transitory intercellular attachments are observed between the central, lateral surfaces of adjacent glomerular epithelial cells in the differentiating renal corpuscle. The junctions are characterized by an increased electron density of the adjacent cell membranes and cytoplasm. The intervening intercellular space may contain an amorphous material of moderate electron density. The distribution and position of such temporary cell attachments, together with their modification and subsequent loss during the differentiation of podocytes, suggest that they play an important role in the histogenesis of the glomerular epithelium.

Repair of the myocardial lesion during potassium repletion of kaliopenic rats: An ultrastructural study

The myocardial lesions of potassium-depleted rats heal with minimal scarring when the animals are repleted with potassium. To elucidate the ultrastructural features of this unique form of myocardial repair, the rats were first depleted of potassium by dietary restriction for 6 weeks. The lesion with myofibral degeneration consisted predominantly of mononuclear cells, many of which contained prominent lysosomal bodies. Interspersed among these cells were small, isolated myofibers which, probably in the process of degeneration, had lost the sarcomeric arrangement of myofilaments as well as most of the organelles. They were partly surrounded by an irregular basal lamina, and contained randomly distributed myofilaments. When the rats were repleted with potassium, the lesions showed a sudden increase of myofibers which resembled those seen during depletion but were in groups with intercellular attachments and encircled by a continuous basal lamina. The interstitial cells during the period of repletion were devoid of lysosomal bodies, and showed proliferation of cytoplasmic organelles. Some of the interstitial cells were partially surrounded by a basal lamina and contained prominent arrays of filaments. They did not, however, appear to be related to the myofibers because of their size and shape. It seemed likely that degenerative myofibers during depletion persisted in an immature form and acted as reserve cells which with repletion of potassium reverted to developing myofibers and ultimately reconstituted the myocardium.

Intercellular attachments between calcified collagenous tissue forming cells in the rat

Osteoblasts of the young rat cranium, and cementoblasts and odontoblasts of young rat molars were prepared by ethanol freeze-fracture prior to critical point drying for scanning electron microscopy (SEM) as well as conventional transmission electron microscopy (TEM) techniques. Critical point drying causes shrinkage which separates the lateral intercellular contacts between neighbours in the same sheet in the case of cementoblasts and osteoblasts, but not those between odontoblasts. These differences are considered to be of functional significance and need to be taken into consideration when formulating theories of calcium influx into the mineralizable matrix of the respective tissues.

Ultrastructural features of chondrogenesis in the human hand plate: a cytochemical and autoradiographic study

ABSTRACT Ultrastructural features of chondrogenesis are correlated with the appearance of collagen and proteoglycan components of the cartilage matrix in the developing human hand (stages 16-18). Prechondral mesenchymal cells comprising the digital plate (stage 16) exhibit euchromatic nuclei, sparse granular endoplasmic reticulum, few polysomes, broad cell to cell associations, little enhancement of electron density after postfixation with osmium tetroxide/potassium ferrocyanide and scanty incorporation of 3H-proline. Extracellular matrix is electron-lucent. During stage 17, early chrondroblasts acquire affinity for OsO4/K4Fe(CN)6, develop filopodia, lose broad intercellular attachments, assemble cytoplasmic polysomes, incorporate 3H-proline and the extracellular matrix acquires electron-dense particles (10-20 nm in diameter). By stage 18, chondrogenic cells of digital blastemata exhibit affinity for osmium-ferrocyanide, and particles (10-20 nm in diameter) and filaments (5 nm in diameter) are present in the extracellular matrix. Mature chondrocytes are present.

Intercellular attachments of cockroach nymph epidermal cells

Junctional complexes on the surfaces of the cockroach nymph epidermal cells are described in detail. Although there are slight modifications, most of the specialized junctions reported in vertebrate and invertebrate epithelial cells are present. In this particular group of epidermal cells, close or gap junctions (20–30 A gap between unit membranes) are reported for the first time in the invertebrates. An unusual finding is the presence of collagen in the intercellular space of the myoepidermal junction. This study suggests morphologically that these epidermal cells are securely anchored to both muscle cells and the cuticle and, furthermore, that they may have lateral communications through septate and gap junctions.

Physiological and morphological effects of poly-L-lysine on the toad bladder

Studies were carried out on the morphological and physiological effects of the binding of poly-L-lysine (polylysine; mol wt≊120,000) to the apical surface membrane of the toad bladder epithelium. Paired hemibladders were mounted in chambers and exposed to polylysine concentrations of 2, 8, or 80 μg/ml in the mucosal medium for periods of up to 2 hr. Radioautographs prepared after addition of(3)H-polylysine showed that the polymer was localized to the apical surface of the epithelium and in dense subapical masses in lysed cells. No significant morphological changes were seen in the epithelium by light or electron microscopy at polymer concentrations of 2 and 8 μg/ml. Exposure to 80 μg/ml lysed many epithelial cells, i.e., converted them to slightly swollen ghosts with pycnotic nuclei and empty cytoplasm, except for remnants of mitochondria and vesicular fragments of the endoplasmic reticulum. All of the superficial epithelial cells were lysed in stretched hemibladders. The plasma membranes of the lysed cells were uniformly thickened, and their intercellular attachments remained intact. In contracted hemibladders, lysed and normal-appearing cells were interspersed, and the number of lysed cells in the epithelium was proportional to the duration of exposure to high concentrations of the polycation. In parallel experiments, the effects of varying concentrations of polylysine on active Na(+) transport and osmotic flow of water were measured with and without vasopressin, aldosterone, or amphotericin B in the media. At a concentration of 2 μg/ml of polylysine in the mucosal bathing solutions, no change in the basal rate of Na(+) transport was seen, and the response to vasopressin was unimpaired. At a concentration of 8 μg/ml, there was a significant but small fall in electrical potential difference (PD) and in short-circuit current (SCC) and no interference with the response to vasopressin. At a concentration of 80 μg/ml, there was a rapid curvilinear fall in SCC to 54±4% of the baseline value and in PD to 21±3% of the baseline value in a 2-hr period. Simultaneous unidirectional isotope flux studies with(22)Na and(24)Na showed a more than twofold increase in the serosal to mucosal flux but no discrepancy between net flux and SCC. Despite the inhibitory action of the polymer, the stimulatory response in Na(+) transport to vasopressin, aldosterone, and amphotericin B was relatively preserved in that the percentage increase in SCC was the same in the polymer-treated and control hemibladders. The polycation produced a small but significant increase in osmotic water flow, and striking and irreversible inhibition of the water-flow response to vasopressin.

An ultrastructural study of early morphogenetic events during the establishment of fetal hepatic erythropoiesis.

Morphogenetic events are described which characterize early stages of the interaction between mesenchyme and expanding epithelial cell cords derived from the hepatic endodermal diverticulum in the C57BL/6J mouse. This interaction culminates in the differentiation of hepatic epithelial and hematopoietic tissues. No basement membrane separates the presumptive hepatic epithelial cells from the adjacent mesenchyme, while intercellular attachments, both adherent junctions and desmosomes, are established transiently between heterologous cell types across this epithelio-mesenchymal interface. Yolk sac-derived erythroblasts found in the primitive liver are distinguished morphologically from endogenous hepatic erythroid cells; they are confined to the vascular compartment and are not, apparently, precursors for hepatic erythropoiesis. The earliest recognizable endogenous hepatic hematopoietic cells appear, extravascularly, among those mesenchymal cells in intimate contact with the endodermal epithelium between the 10(1/4) and 10(1/2) gestational day. Definitive erythropoiesis commences between the 10(1/2) and 11th fetal days. The ultrastructure of these primitive hepatic erythroid cells (proerythroblasts) and their transition to more mature forms (basophilic and polychromatophilic erythroblasts) are described.

A Cutaneous Clue to Mammary Carcinoma

The first of the three illustrations should cause no concern. The condition pictured in Fig 1 will respond to proper antipsoriasis therapy. However, Fig 2 and 3 illustrate a condition which requires prompt surgical intervention. The difficulty involved in the clinical distinction between the benign lesion of psoriasis and the malignant lesion of Paget's disease of the nipple is obvious. In Paget's disease of the nipple, the normal epidermal cells are replaced by large, pale-staining cells which lack the normal intercellular attachments of epidermal cells. In addition their cytoplasm stains positively for mucin when the alcianblue technique is used. These pale large cells are malignant in themselves, and are always associated with an underlying mammary carcinoma which is usually of the intraductal type. Presumably, the malignant ductal cells proliferate up the duct and eventually out into the epidermis of the nipple. There they do not form a tumor mass but

Junctional structure of smooth muscle cells: The ultrastructure of the regions of junction between smooth muscle cells in the rat small intestine

The electron micrographs obtained in this study revealed that there are two kinds of contact zones between smooth muscle cells in the rat small intestine—those with fusion of adjoining plasma membranes and those with intercellular attachments. The pattern of the former is characterized by fusion of the adjoining plasma membranes resultin in obliteration of the intercellular space. Within the obliterated areas the outer layers of the adjoining plasma membranes fuse to form a single intermediate line. The pattern of the latter is characterized by the presence of an intercellular space (30–100 A wide) occupied by a homogeneous and amorphous material of moderate density, by strict parallelism of the adjoining plasma membranes and by an increased density of the cytoplasmically opaque material attached to the plasma membranes.