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  • 1
    Electronic Resource
    Electronic Resource
    Expression of gap junction genes, connexin40 and connexin43, during fetal mouse development (1995)
    Springer
    Anatomy and embryology 191 (1995), S. 267-278 
    Details
    ISSN: 1432-0568
    Keywords: Fetal mouse development ; Connexin40 ; Connexin43 ; Myotubes ; Endothelial cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The expression patterns of the gap junction genes connexin40 and connexin43 have been analyzed during late mouse fetal development, i.e., at embryonic days 14.5 and 16.5, by in situ hybridization and immunofluorescence. Connexin40 was found in endothelial cells of vessels, cardiomyocytes and in developing myoblasts and myotubes. Expression of connexin40 in developing muscle fibers was strong in the back muscles and weaker in the muscles of the limbs. The number of labeled cells in the back muscle decreased with ongoing differentiation of myoblasts, in accordance with the idea that connexin40 is only expressed in the early stages of muscle cell differentiation. Within a muscle bundle, connexin40 expression was predominantly found at the outermost side where myoblasts fuse to multinucleated myotubes. In contrast, connexin43 exhibits a wide and complex pattern of expression in fetal mouse development. It is found in organs originating from all three germ layers, such as epidermis, heart, lung, muscle, kidney and gut. Connexin43 transcript and protein were very abundant in tissues that had been undergoing inductive interactions, e.g., the inner enamel epithelium of the teeth, the glomeruli of the kidneys and the infundibulum forming the neural part of the pituitary gland. Very high connexin43 expression was found in the embryonic meninges (dura mater) and in the fetal adrenal cortex. During keratinocyte differentiation connexin43 mRNA expression decreased, being much stronger in the stratum basale than in stratum granulosum. No obvious discrepancy between the amount of mRNA and protein of either connexin was noticed, suggesting that there is no specific translational regulation at these developmental stages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00187825
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  • 2
    Electronic Resource
    Electronic Resource
    Spatial and Temporal Expression of Connexin26 and Connexin43 in Rat Endometrium during Trophoblast Invasion
    Amsterdam : Elsevier
    Developmental Biology 157 (1993), S. 399-409 
    Details
    ISSN: 0012-1606
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1006/dbio.1993.1144
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  • 3
    Electronic Resource
    Electronic Resource
    Gap junction formation in rabbit uterine epithelium in response to embryo recognition
    Amsterdam : Elsevier
    Developmental Biology 126 (1988), S. 203-211 
    Details
    ISSN: 0012-1606
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0012-1606(88)90254-0
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  • 4
    Electronic Resource
    Electronic Resource
    GAP JUNCTION AND TISSUE INVASION: A COMPARISON OF TUMORIGENESIS AND PREGNANCY (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 23 (1996), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. Trophoblast invasion during embryo implantation in some aspects resembles tumour cell invasion but, unlike tumour cells, trophoblast cells are able to differentiate and establish a placenta. Because direct cell-cell communication is believed to be involved in growth control and differentiation, we have investigated connexin (cx) gene expression during trophoblast development.2. he-implantation embryos expressed cx43 as well as ex31 proteins from the 8-cell stage onwards. Following implantation, compartmentalization of both connexins occurred: cx31 expression was restricted to the invasive trophoblast cell population, whereas the embryo proper was characterized by cx43. Trophoblast differentiation was indicated by induction of cx26 in the labyrinth and cx43 in the spongiotrophoblast accompanied by a disappearance of cx31. Comparison with trophoblast cell lines revealed that rat trophoblast HRP-1 cells express connexin43, while malignant choriocarcinoma cells express cx31. Treatment with retinoic acid led to a disappearance of cx31 in the choriocarcinoma. Both cell lines reduced their invasion properties after retinoic acid treatment, but growth retardation was only observed in the malignant trophoblast.3. It seems that the cx31 channel is needed for trophoblast cell populations to maintain the highly proliferative properties but does not alter their invasion properties.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1996.tb01169.x
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  • 5
    Electronic Resource
    Electronic Resource
    The Gap Junctional Protein Connexin(Cx)43 in Testicular Cancer: its Loss Marks Progession from Carcinoma In Situ to Invasive Germ Cell Tumour (2005)
    Berlin, Germany : Blackwell Verlag GmbH
    Anatomia, histologia, embryologia 34 (2005), S. 0 
    Details
    ISSN: 1439-0264
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Carcinoma-in-situ (CIS) of the testis is known to be the pre-invasive stage of most human germ cell tumours (seminoma and non-seminoma), but the mechanisms leading to an increased pubertal proliferation of CIS cells after a long latency and to progression of CIS to an invasive malignancy are still not known. Additionally, CIS and seminoma have also been reported in equine testis (Veeramachaneni and Sawyer, 1998). The gap junctional protein and tumour suppressor gene connexin(cx)43 represents the predominant cx in human, canine and rodent testis so far and it is expected to play a key role for the regulation of both proliferation and differentiation of germ cells (spermatogonia and spermatocytes), and its gene- and protein-expression pattern is typical for the pubertal terminal differentiation of somatic Sertoli cells. Using cDNA-microarray analysis, in-situ hybridization (ISH), RT-PCR from tissue homogenate and semi-quantitative RT-PCR from well defined microdissected tubules with normal spermatogenesis, CIS, intratubular seminoma (ISe) and from seminoma cells from invasive seminoma we found a downregulation of cx43 starting in intratubular CIS, leading to a complete loss in most invasive seminoma cells. This indicates that regulation of cx43 expression takes place at transcriptional level confirming and expanding earlier studies of protein expression (Brehm et al., 2002). This reduction of cx43-expression suggests that an early intratubular derangement in cx43-gene expression and disruption of inter-cellular communication between Sertoli cells and/or Sertoli cells and pre-invasive tumour cells via cx43-gap junctions may play a role in the proliferation of CIS cells and seminoma cells and in the progression phase of testicular seminoma development.References  Veeramachaneni, D. N., and H. R.Sawyer, 1998: Carcinoma in situ and seminoma in equine testis. APMIS 106, 183–185.Brehm R., A. Marks, R. Rey, S. Kliesch, M. Bergmann and K. Steger, 2002: Altered expression of connexins 26 and 43 in Sertoli cells in seminiferous tubules infiltrated with carcinoma-in-situ or seminoma. J. Pathol. 197, 647–653.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1439-0264.2005.00669_16.x
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  • 6
    Electronic Resource
    Electronic Resource
    Apical plasma membrane-bound enzymes of rabbit uterine epithelium (1987)
    Springer
    Histochemistry and cell biology 87 (1987), S. 517-529 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In order to monitor changes in the apical cell membrane of rabbit uterine epithelium which are postulated to be a precondition for trophoblast attachment, the marker enzymes: alkaline phosphatase, aminopeptidase M, γ-glutamyl transferase and dipeptidyl peptidase IV were investigated during the periimplantation phase. Endometrium of early pregnancy (implantation chamber, interblastocyst endometrium; 5–8 days post coitum, d p.c.) was compared with specimens obtained at hCG-induced pseudopregnancy (p. hCG) to distinguish between membrane changes regulated by maternal plasma steroid hormones and such which might be induced locally by blastocyst-derived signals. All enzymes tested showed their main activity at 5 d p.c./p. hCG. The weakest reaction in this series of stages was generally found at 8 d p.c. (interblastocyst segments) or at 8 d p. hCG. In contrast to the rest of the epithelium, the implantation chamber retained high activity of dipeptidyl peptidase IV, and the activity of alkaline phosphatase even raised here again at 7 and 8 d p.c. indicating a direct local influence of the blastocyst on the luminal epithelium. The results suggest that 1) considerable changes occur in the composition of the apical plasma membrane of the uterine epithelium when the endometrium enters the “receptive state”, 2) the overall trend is towards a loss of apical-type characteristics of this membrane domain and 3) the changes are modulated both systemically (by plasma steroid hormone levels) and locally by signals from the implanting blastocyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00492466
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  • 7
    Electronic Resource
    Electronic Resource
    Regulation of gap junction connexins in the endometrium during early pregnancy (1998)
    Springer
    Cell & tissue research 293 (1998), S. 189-194 
    Details
    ISSN: 1432-0878
    Keywords: Key words Connexin ; Implantation ; Receptive phase ; Endometrium ; Gap junction ; Hormonal regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In mammalian species embryo implantation into uterine tissue is restricted to a limited time period, the receptive phase. For successful implantation appropriate differentiation of the receptive endometrium is under the control of ovarian steroid hormones. In addition, locally acting embryonic signals are needed to modulate the maternal environment before invasion of the trophoblast is permitted. The expression pattern of gap junction channel proteins, connexins (cx), is directly related to this process. In rodents as well as in rabbit and humans the receptive endometrium is characterized by a lack of such cell-to-cell communication channels. In the rat endometrium cx26 is suppressed in the epithelium and cx43 in the stromal compartment by maternal progesterone, a phenomenon that can be observed similarly in human endometrium. Experimental approaches revealed that both connexin genes react very sensitively to progesterone and estrogen treatment. In rat and rabbit connexin expression is induced locally in the endometrium in response to the implanting blastocyst. In both species this induction of connexins can be mimicked by a traumatic stimulus. In conclusion, suppression of connexin expression in the endometrium is a characteristic cell biological indication for receptivity in different species. The limited induction of direct cell-to-cell communication properties, probably due to locally acting blastocyst signals, seems to be a precondition for embryo implantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051111
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  • 8
    Electronic Resource
    Electronic Resource
    Rabbit endometrium in organ culture: Morphological evidence for progestational differentiation in vitro (1989)
    Springer
    Cell & tissue research 257 (1989), S. 505-518 
    Details
    ISSN: 1432-0878
    Keywords: Endometrium ; Organ culture ; Steroid hormones ; Membrane fusion ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This communication describes conditions for long-term organotypic culture of rabbit endometrium allowing progesterone-induced transformation, as typcial for early pregnancy, to continue in vitro. This system appears to compare favorably with in vitro models so far proposed for the study of hormonal control of uterine function or for the investigation of cell-biological aspects of embryo implantation. The specific aim in the presented system is to provide approximate normal epithelium-stroma interrelationships. Fragments of endometrium consisting of epithelium and stroma were obtained during early pseudopregnancy and cultured on a gyratory shaker. Morphology was investigated by light microscopy, transmission and scanning electron microscopy. During the first two days the epithelium grows over the exposed stroma regenerating a complete epithelial lining. No central necrosis is found in the stroma for up to 6 days, and the tissue keeps its organotypic architecture although certain morphological differences can be observed between regenerated versus original epithelium. In the regenerating portion a stage-specific cell differentiation and the reformation of a basal lamina are missing. Progesterone substitution preserves cell morphology and allows to maintain, in vitro, the stage-specific pattern of cell organelles. Most characteristic is the induction of extensive fusion of epithelial cells. These large symplasms are comparable in size and structure to those formed in pregnancy in the implantation chamber in vivo. Only the superficial parts of the original (not the regenerated) epithelium are capable of progesterone-induced large-scale fusion. This organotypical culture system appears to be of potential value for in vitro studies on hormone action and on endometrial receptivity for embryo implantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00221460
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of hyper- and hypoosmotic solutions on the structure of theAstacus retina (1982)
    Springer
    Cell & tissue research 223 (1982), S. 267-280 
    Details
    ISSN: 1432-0878
    Keywords: Retina (Astacus) ; Rhabdom ; Osmolarity ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Alterations of the retinula cells in the retina of the light-adapted crayfish in response to hyper- and hypoosmotic van Harreveld solutions was examined by transmission electron microscopy. Increased osmolarity of the bathing medium to twice that of the physiological value leads to shrinkage of the retinula-cell somata. Microvilli, on the other hand, do not undergo shrinkage. Some other characteristic irreversible changes do, however, take place, including detachment of microvilli from the soma, showing a two- or threefold increase in diameter, and a concomitant decrease in number, probably due to fusion of microvilli. Prolonged incubation or higher osmolarities (5 isosmol) cause alteration of the microvillar membranes to whorls. Structural changes are often restricted to microvillar stacks evaginating from certain individual retinular cells. The number of affected stacks increases depending on the duration of incubation or the osmotic pressure. Hypoosmotic solution (0.5 isosmol) also induces an increase of microvillar diameters and a concomitant reduction in number of microvilli per stack. Exposure to a 20% solution of glycerol causes destruction of the rhabdom structure and the formation of whorls from microvillar membranes. The present findings suggest that the structure of the microvilli is stabilized by an axial cytoskeleton.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01258488
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  • 10
    Electronic Resource
    Electronic Resource
    Membrane events involved in fusion of uterine epithelial cells in pseudopregnant rabbits (1984)
    Springer
    Cell & tissue research 235 (1984), S. 357-363 
    Details
    ISSN: 1432-0878
    Keywords: Membrane fusion ; Uterine epithelial cells ; Pseudopregnancy ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary During pseudopregnancy in the rabbit some uterine epithelial cells undergo conversion into symplasmata. This event serves as a model for studies of membrane apposition, fusion and fission of the lateral membranes with the use of different ultrastructural techniques. Apposition of lateral membranes occurs by means of proliferation of the tight-junctional belt and macular tight junctions. Membrane fusion is characterized in freeze-fracture replicas by continuously running fracture planes between neighboring membrane leaflets of epithelial cells, in general without reorganization of the particles. It is suggested that the reorganization of particles as well as the blebs or vesicles of smooth membranes, which are occasionally observed, may be artefacts. Membrane fission occurs simultaneously with fusion resulting in irregularly shaped membrane holes on freeze-fracture replicas. These events are rarely seen in thin sections. Staining with tannic acid reveals that only the layers of the plasma membrane are accessible to this agent. The fusion-fission process starts in the lower region of the lateral membranes, whereas the luminal portion with the broad tight-junctional belt remains intact.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217860
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