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  • 1
    Electronic Resource
    Electronic Resource
    Unrestricted lineage differentiation of parthenogenetic ES cells (1997)
    Springer
    Development genes and evolution 206 (1997), S. 377-388 
    Details
    ISSN: 1432-041X
    Keywords: Key words Cell potency ; Lineage differentiation ; Genomic imprinting ; Parthenogenetic embryos ; Chimaeras
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The developmental potential of parthenogenetic embryonic stem (P-ES) cells was studied in teratomas and mouse chimaeras. Teratomas derived from P-ES cells contained a mixture of tissue types with variable proportions of specific tissues. Three of the eight P-ES cell lines analysed showed high proportions of striated muscle in teratomas, similar to teratomas from normal embryos or ES cell lines derived from fertilised embryos (F-ES cells). Our study also revealed that one P-ES cell line showed little lineage restriction in injection chimaeras. Descendants of the P-ES cells contributed to most tissues of chimaeric fetuses in patterns similar to F-ES cells. Normal colonisation of muscle, liver and pancreas was found in adult chimaeras. P-ES cells also showed similar haematopoietic differentiation and maturation as F-ES cells. However, extensive P-ES cell contribution was associated with a reduction in body size. These findings suggest that, while P-ES cells display more extensive developmental potential than the cells of parthenogenetic embryos from which they were derived, they only retained properties related to the presence of the maternal genome. To elucidate the molecular basis for the lack of lineage restriction during in vivo differentiation, the expression of four imprinted genes, H19, Igf2r, Igf2 and Snrpn was compared among five P-ES and two F-ES cell lines. Expression levels of these genes varied among the different ES cell lines, both in undifferentiated ES cells and in embryoid bodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050067
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  • 2
    Electronic Resource
    Electronic Resource
    Specification and segmentation of the paraxial mesoderm (1994)
    Springer
    Anatomy and embryology 189 (1994), S. 275-305 
    Details
    ISSN: 1432-0568
    Keywords: Paraxial mesoderm ; Segmentation ; Somitogenesis ; Somitomeres ; Mesoderm specification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Somite formation in the mouse embryo begins with the recruitment of mesenchymal cells into the paraxial mesoderm. Cells destined for the paraxial mesoderm are recruited from a progenitor population found first in the embryonic ectoderm and later in the primitive streak and the tail bud. Experimental evidence suggests that the allocation of precursor cells to different mesodermal lineages may be related to the site at which the cells ingress through the primitive streak. An increasing number of genes, such as those encoding growth factor and transcription factors, are now known to be expressed in the primitive streak. It is not known whether the specification of mesodermal cell fate has any relationship with the activity of genes that are expressed in the restricted cell populations of the primitive streak. Somitomeres, which are spherical clusters of mesenchymal cells in the presomitic mesoderm, presage the segmentation of somites in the paraxial mesoderm. The somitomeric organization denotes a pre-pattern of segmentation that defines the physical boundary and the bilateral symmetry of the mesodermal segments in the body axis. The establishment of new somitomeres seems to require the interaction of a resident cell population in the presomitic mesoderm and the incoming primitive streak cells. Cell mixing, which occurs in the somitomeres prior to somite segmentation, poses problems in understanding the developmental role of the somitomere and the real significance of the partitioning of the node-derived and primitive streak-derived cells in the mesodermal segments. In the presomitic mesoderm, the expression of some genes that encode transcription factors, growth factors or tyrosine kinase receptor, and the localization of certain cell adhesion molecules are closely associated with distinct morphogenetic events, such as cell clustering in the presomitic mesoderm and the formation of epithelial somites. There is, however, very little direct relationship between the spatial pattern of gene expression and the somitomeric organization in the presomitic mesoderm. Results of somite transplantation experiments suggest that both the segmental address and the morphogenetic characteristics of the somite may be determined during somite segmentation. Regional identity of the paraxial mesodermal segment is conferred by the expression of a combination of Hox genes in the sclerotome and probably other lineage-specific genes that are subject to imprinting. Superimposed on the global metameric pattern, two orthogonal polarities of cell differentiation are endowed in each mesodermal segment. The rostro-caudal polarity is established prior to somite segmentation. This polarity is later manifested by the subdivision of the sclerotome and the alliance of the neural crest cells and motor axons with the rostral half-somite. The dorso-ventral polarity is installed after somite segmentation, probably by an inductive mechanism similar to that which specifies the dorso-ventral pattern of neuronal differentiation in the neural tube. The segmental pattern of the paraxial mesoderm has been found to exert a direct impact not only on the morphogenesis of the vertebral column, but also on the segmental organization of the lateral mesoderm, the peripheral nervous system and the craniofacial structures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00190586
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  • 3
    Electronic Resource
    Electronic Resource
    Genomic imprinting Mice without a father (2004)
    [s.l.] : Nature Publishing Group
    Nature 428 (2004), S. 809-811 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sexual reproduction in animals ensures that each individual normally inherits one set of genes from each parent. But viable offspring that have only maternal genes — none from the father — can be produced through parthenogenetic reproduction in plants and most groups of animals. A ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/428809a
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  • 4
    Electronic Resource
    Electronic Resource
    A specific requirement for PDGF-C in palate formation and PDGFR-α signaling (2004)
    [s.l.] : Nature Publishing Group
    Nature genetics 36 (2004), S. 1111-1116 
    Details
    ISSN: 1546-1718
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] PDGF-C is a member of the platelet-derived growth factor (PDGF) family, which signals through PDGF receptor (PDGFR) αα and αβ dimers. Here we show that Pdgfc−/− mice die in the perinatal period owing to feeding and respiratory difficulties associated with a ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/ng1415
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  • 5
    Electronic Resource
    Electronic Resource
    A gut feeling (2005)
    [s.l.] : Nature Publishing Group
    Nature biotechnology 23 (2005), S. 1491-1492 
    Details
    ISSN: 1546-1696
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: [Auszug] If embryonic stem (ES) cells are to revolutionize regenerative medicine, scientists must find efficient ways of producing the desired differentiated cell types. Two papers in this issue outline methods for differentiating mouse and human ES cells to definitive endoderm, the embryonic germ layer ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nbt1205-1491
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  • 6
    Electronic Resource
    Electronic Resource
    The in vitro fertilization program at the Chinese University of Hong Kong (1986)
    Springer
    Journal of assisted reproduction and genetics 3 (1986), S. 336-337 
    Details
    ISSN: 1573-7330
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01133398
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  • 7
    Electronic Resource
    Electronic Resource
    A correlation of the outcome of clinical in vitro fertilization with the inositol content and embryotrophic properties of human serum (1992)
    Springer
    Journal of assisted reproduction and genetics 9 (1992), S. 524-530 
    Details
    ISSN: 1573-7330
    Keywords: inositol ; human sera ; embryotrophic property ; in vitro fertilization ; postimplantation mouse embryo culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Methods The embryotrophic properties of human serum were evaluated by the development of postimplantation mouse embryos [in vitro assay of Tam et al.(Fertil Steril 48:834–839, 1987)].An enzymatic spectrophotometric method using myo-inositol dehydrogenase was used for determination of serum MI. The level of MI detected in serum was compared with the embryotrophic properties and the pregnancy outcome. The effect of MI on the embryotrophic activity of human serum was studied by supplementing the suboptimal serum samples that were unsupportive of embryo growth with extra MI.
    Abstract: Results Serum obtained from patients having successful IVF pregnancies generally supported better development of postimplantation mouse embryos and contained higher levels of inositol, particularly if the serum sample was collected during the IVF treatment cycle. Serum samples obtained from patients with aborted pregnancies, though supporting mouse embryo development, contained significantly lower concentrations of inositol. An improvement of the embryotrophic properties with exogenous inositol supplement was achieved in some but not all of the suboptimal serum samples studied.
    Notes: Purpose This study was designed to investigate whether the level of myo-inositol (MI) in human serum is critical for embryotrophic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01204248
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  • 8
    Electronic Resource
    Electronic Resource
    Cephalic neurulation in the mouse embryo analyzed by SEM and morphometry (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 203 (1982), S. 375-396 
    Details
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A detailed account of mouse neurulation is given based mostly on SEM analysis over 20 hr of development. Many observations and measurements were made on staged living embryos and on embryos prepared for scanning and light microscopy to help deduce what mechanisms may contribute to neural tube formation. Each-lateral half of the early cephalic neural plate makes a convex bulge, opposite to the way it must fold to form a tube. Underlying mesenchyme and matrix are reported to have a role in forming these bulges. Processes that form the tube must overcome this opposed folding and the forces that produce it. Cranial flexure begins long before tube formation. The flexure commences at the rostral tip of the cephalic neural plate, then the apex of the flexure migrates caudally to the mesencephalic region. Early appearance of this flexure imposes a mechanical impediment to tube closure in forebrain and midbrain regions. Tube closure begins in the cervical region exactly where the neural plate is reflected dorsally by a bend in the embryo. This bend may mechanically assist closure in this region. Cells of the mouse neural plate are reported to contain organized microfilaments and microtubules, and the plate cells appear to change shape (reduce apical area and increase cell height) in the same manner as that suggested in embryos of some other species to contribute to neural tube formation. Measurements show that the lateral edges of the cephalic neural plate elongate craniocaudally more than the midline of the plate through each period. This elongation could contribute to the folding of the plate into a tube. The progress of cranial ventral flexure pauses while tube formation occurs, but edge elongation continues, presumably contributing to tube formation. There is considerable increase in volume of the neural plate during tube closure, and cell proliferation and enlargement of daughter cells seem sufficient to account for this growth. Mitotic spindles are positioned to place the majority of the daughter cells into the long axis of the neural plate, so ordered growth may be the main mechanism of elongation of the plate in the craniocaudal direction, which in turn may assist in tube formation. Mouse cephalic neural plates appear overlying already segmented cranial mesenchyme according to previous reports, and neuromeres develop precociously in the open plates, where their positions correlate exactly with the underlying segmented mesenchyme.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/ar.1092030308
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  • 9
    Electronic Resource
    Electronic Resource
    Changes in metabolism and hepatic ultrastructure induced by estradiol and testosterone in immature female Epinephelus akaara (Teleostei, Serranidae) (1984)
    Springer
    Cell & tissue research 236 (1984), S. 651-659 
    Details
    ISSN: 1432-0878
    Keywords: Steroids ; Vitellogenesis ; Metabolism ; Ultrastructure ; Teleosts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Estradiol injections increase serum level of calcium, amino acid, glucose, protein, ammonia and creatinine in immature Epinephelus akaara, and also increase levels of total lipid, cholesterol, phospholipid and esterified fatty acids. Hepatic protein, glycogen and lipid concentrations also rise after estradiol treatment, and some hepatic enzymes participating in the metabolism of nitrogen, lipid and carbohydrate, show increased activity. Serum vitellogenin levels are increased. Testosterone treatment increases serum protein, total lipid, cholesterol, amino acid and ammonia levels, and also hepatic glycogen content, but in contrast to estradiol treatment, testosterone does not change serum vitellogenin, glucose, calcium, phospholipid, esterified fatty acid and creatinine levels, nor the hepatic lipid and protein content. A small number of hepatic enzymes shows an increased activity. Vitellogenic fish show biochemical changes similar to that of estradiol-treated fish, but are different from those of immature fish. Estradiol treatment induces ultrastructural changes in the hepatocytes of immature fish that are similar to those found in vitellogenic fish. These include a proliferation of rough endoplasmic reticulum and Golgi apparatus, and an increase in glycogen and lipid, all indicative of enhanced metabolic activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00217235
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  • 10
    Electronic Resource
    Electronic Resource
    Regionalisation of cell fate and morphogenetic movement of the mesoderm during mouse gastrulation (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Developmental Genetics 17 (1995), S. 16-28 
    Details
    ISSN: 0192-253X
    Keywords: Mesoderm ; fate-mapping ; germ layer formation ; morphogenetic movement ; Life and Medical Sciences ; Genetics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology
    Notes: The developmental fate of cells in the epiblast of early-primitive-streak-stage mouse embryos was assessed by studying the pattern of tissue colonisation displayed by lac Z-expressing cells grafted orthotopically to nontransgenic embryos. Results of these fate-mapping experiments revealed that the lateral and posterior epiblast contain cells that will give rise predominantly to mesodermal derivatives. The various mesodermal populations are distributed in overlapping domains in the lateral and posterior epiblast, with the embryonic mesoderm such as heart, lateral, and paraxial mesoderm occupying a more distal position than the extraembryonic mesoderm. Heterotopic grafting of presumptive mesodermal cells results in the grafted cells adopting the fate appropriate to the new site, reflecting a plasticity of cell fate determination before ingression. The first wave of epiblast cells that ingress through the primitive streak are those giving rise to extraembryonic mesoderm. Cells that will form the mesoderm of the yolk sac and the amnion make up a major part of the mesodermal layer of the midprimitive-streak-stage embryo. Cells that are destined for embryonic mesoderm are still found within the epiblast, but some have been recruited to the distal portion of the mesoderm. By the late-primitive-streak-stage, the mesodermal layer contains only the precursors of embryonic mesoderm. This suggests that there has been a progressive displacement of the midstreak mesoderm to extraembryonic sites, which is reminiscent of that occurring in the overlying endodermal tissue. The regionalisation of cell fate in the late-primitive-streak mesoderm bears the same spatial relationship as their ancestors in the epiblast prior to cell ingression. This implies that both the position of the cells in the proximal-distal axis and their proximity to the primitive streak are major determinants for the patterning of the embryonic mesoderm. © 1995 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/dvg.1020170104
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