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  • 1
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] For the targetted deletion of the α7-integrin gene, we replaced 1 kb of genomic sequence, including the part of exon 1 that encodes its signal sequence, and the first 107 bp of the mature protein12, with a phosphoglycerate-kinase–neomycin (PGK-neo) cassette by homologous recombination ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Anatomy and embryology 192 (1995), S. 275-281 
    ISSN: 1432-0568
    Keywords: Basement membrane ; Mouse embryo ; Reichert's membrane ; Tannic acid fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Although the composition of Reichert's membrane, a thick multilayered basement membrane between the parietal endoderm cells and the trophoblast cells of rodents, has often been investigated, the site of its production remains a subject of controversial discussion. In particular, the role of the trophoblast cells is unclear. In the present work we examined the initial development of Reichert's membrane in the early mouse embryo, using glutaraldehyde fixation with tannic acid. In the early blastocyst the occurrence of a tannic-acid-positive layer located at the inner surface of the mural trophoblast indicated the onset of basement membrane formation by the trophoblast cells. In the peri-implantation phase, this basement membrane extended into lateral areas of the inner cell mass separating the newly differentiated ectoderm and endoderm cells from each other. In these lateral regions, where the recently formed primitive endoderm cells had been attached to the monolayered basement membrane of the mural trophoblast, the membrane began to reveal the typical multilayered structure of Reichert's membrane. Our findings indicate that the initial formation of Reichert's membrane begins with the formation of a basement membrane of the mural trophoblast cells, followed by an apposition of basement membrane material, probably synthesized by primitive endoderm cells, along this primary membrane.
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  • 3
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  There is evidence that basement membrane components control differentiation of liver sinusoids and bile ducts. These processes occur in humans in the 9th gestational week (GW). Distribution of laminin, nidogen, and type IV collagen was studied during human liver development between the 6th and the 10th GW. Laminin and nidogen lined intrahepatic microvessels in the 6th and 7th GW decreasing in quantity at the beginning of the fetal period (9th–10th GW). Type IV collagen was detected in microvessels only from the 9th GW onward. In the early periportal matrix (9th–10th GW) laminin, nidogen, and type IV collagen were diffusely distributed. At these stages, basement membrane zones of larger portal vessels and of early bile ducts were also stained for all three glycoproteins. These results show that laminin and nidogen are localized in microvessels during early human liver development and decrease in concentration at the developmental stage during which microvessels become discontinuous. In contrast, type IV collagen is not present in early microvessels but occurs when laminin and nidogen disappear. The three glycoproteins occur together only in those areas of the developing liver in which, from the 9th GW onward, the differentiation of immature liver cells into biliary epithelium takes place.
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  • 4
    ISSN: 1432-0878
    Keywords: Key words: Small proteoglycans ; Intervertebral disc ; Decorin ; Biglycan ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Immunohistochemistry was used to study the presence and distribution of the core proteins of the small proteoglycans decorin and biglycan in the various compartments of human intervertebral discs. Both proteoglycans could be found in the outer tendon-like parts of the annulus fibrosus, indicating their potential role in collagen network formation and biomechanical stress resistance. The loss of both proteoglycans in the annulus of individuals older than 50 years reflects a normal age-related change. In the nucleus pulposus, decorin could be found in fibrillar areas of the interterritorial matrix, thereby indicating co-localization of decorin with fibrils containing type II collagen. Biglycan was present in the extracellular matrix of the nucleus pulposus of adults. The pericellular immunoreactive rims observed around nucleus pulposus cells and giant chondrones indicated local biosynthetic activity for these small proteoglycans. The staining patterns in cartilage endplates resembled those found in human hyaline articular cartilage.
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  • 5
    ISSN: 1432-0878
    Keywords: Key words Histone H1t ; Spermatogenesis ; Immunogold staining ; In situ hybridization ; Western blot analysis ; Mouse (NMRI)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The gene encoding H1t, a testicular variant of histone H1, is expressed in mammals during spermatogenesis. Northern blot and in situ hybridization has detected H1t mRNA only at the stage of pachytene spermatocytes. We have extended this analysis to more sensitive approaches and demonstrate, by RNase protection and electron-microscopic in situ hybridization, that H1t mRNA is detectable even in spermatogonia. Just a faint H1t band is seen in Western blots of nuclear protein from 9-day-old mice. This indicates that the H1t gene is expressed at premeiotic stages, albeit at a low level. In contrast to H1t mRNA, the H1t protein has not been detected in spermatogonia by electron microscopy after immunogold staining.
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  • 6
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fibulin-1 and fibulin-2, two recently identified extracellular matrix proteins with a homologous domain structure, are known to bind various extracellular ligands and calcium. In this study, they have been localized at the light microscopical level in human embryos of gestational weeks 4–10, using polyclonal antibodies. Identical localization patterns were observed for the two fibulins in most of the tissues. In the heart, the endocardial cushion tissue and endocardium, but not the myocardium, were stained, as were the basement membrane zones and adventitia of blood vessels. Staining was also observed in the perichondrium and calcifying regions of developing bones. Moreover, reactions occurred with the gut subepithelium and epithelial basement membranes of the skin. Differences in staining patterns, however, were observed in various neural structures. Fibulin-1 was prominent in the matrix of the leptomeningeal anlage, in basement membranes of the neuroepithelium and the perineurium of peripheral nerves. Fibulin-2 was detected primarily within the neuropithelium, spinal ganglia and peripheral nerves. The early embryonic expression of both fibulins indicates specific roles during organ development and, in particular, involvement in the differentiation of heart, skeletal and neuronal structures.
    Type of Medium: Electronic Resource
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