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  • Life and Medical Sciences  (61)
  • Food Science, Agricultural, Medicinal and Pharmaceutical Chemistry  (3)
  • Wiley-Blackwell  (64)
  • American Meteorological Society (AMS)
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 185 (1985), S. 101-114 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Paraffin sections of an ontogenetic series of embryos of the viviparous lizard Gerrhonotus coeruleus and the oviparous congener G. multicarinatus reveal that although general features of the development of the chorioallantoic and yolk sac membranes are similar, differences are evident in the distribution of the chorioallantoic membrane in late stage embryos. An acellular shell membrane surrounds the egg throughout gestation in both species although the thickness of this structure is much reduced in G. coeruleus over that of G. multicarinatus. The initial vascular membrane to contact the shell membrane in both species is a trilaminar omphalopleure (choriovitelline membrane) composed of ectoderm, mesoderm of the area vasculosa, and endoderm. This transitory membrane is replaced by the vascularized chorioallantois as the allantois expands to contact the inner surface of the chorion. Prior to the establishment of the chorioallantois at the embryonic pole, a membrane begins to form within the yolk ventral to the sinus terminalis. This membrane, which becomes vascularized, extends across the entire width of the abembryonic region and isolates a mass of yolk ventral to the yolk mass proper. The outer membrane of the yolk pole is a nonvascular bilaminar omphalopleure (chorionic ectoderm and yolk endoderm). In G. multicarinatus the bilaminar omphalopleure is supported internally by the vascularized allantoic membrane, whereas in G. coeruleus the allantois does not extend beyond the margin of the isolated yolk mass and the bilaminar omphalopleure is supported by the vascularized intravitelline membrane. Both the chorioallantoic placenta (uterine epithelium, chorionic ectoderm and mesoderm, and allantoic mesoderm and endoderm) and the yolk sac placenta at the abembryonic pole (uterine epithelium, chorionic ectoderm, and yolk sac endoderm) persist to the end of gestation in G. coeruleus.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 223 (1995), S. 149-166 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study investigates the effect of developmental stage on thyroid hormone (TH)-mediated remodeling in the skeletal tissues of hemidactyliine plethodontid urodeles. Rate of morphogenesis was quantified in 17 metamorphic tissues for three different size-age classes of Eurycea bislineata larvae immersed in a metamorphic dosage of T4. Extent of morphogenesis after a 3-week immersion was also quantified in these tissues plus four larval ones for the full size range of E. bislineata larvae and for less complete size ranges of E. wilderae, E. longicauda guttolineata, Gyrinophilus porphyriticus, and Pseudotriton ruber larvae. Although all tissues respond more slowly with decreasing size/age, two tissue-specific effects are evident in all species. Larval ossifications are less inducible than metamorphic ossifications, and progressive metamorphic events are more retarded and, in some cases, more prone to abnormal morphogenesis than regressive ones. The first effect agrees with the prediction that tissues that naturally remodel at metamorphosis are more responsive to a metamorphic dosage of TH than those that respond at a larval stage and lower TH. The second effect agrees with the prediction that progressive morphogenesis is more likely to be impaired at small size than regressive morphogenesis, although the frequent discrepancies between individuals of similar size implicate developmental age more than size in this effect. Collectively, these two effects provide only equivocal support for the hypothesis that direct development in plethodontids evolved via precocious TH activity. However, the unexpected transition from ceratobranchial replacement to ceratobranchial shortening in medium-sized larvae suggests that the former pathway requires a longer period of cell specification at low TH. Since ancestral plethodontids appear to have been distinguished by an exceptionally long larval period with exceptionally low TH activity, this developmental prerequisite may in turn be partly responsible for their singular evolution of ceratobranchial replacement. © 1995 Wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 139 (1973), S. 377-388 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The Oberhautchen of scales from the dorsal, parietal, and ventral regions of Sceloporus occidentalis (Iguanidae), Gerrhonotus multicarinatus (Anguinidae), and Anniella pulchra (Anniellidae) were examined with a scanning electron microscope. At low magnification, all scales of S. occidentalis exhibit well-defined outlines of cells belonging to the Oberhautchen layer and the previously overlying clear layer. The dorsal and parietal cells of this species exhibit a minutely dentate Oberhautchen that forms tooth-like spinules 0.2 to 0.5 μ long and arranged in irregular rows. Minute pits 0.1 to 0.3 μ in diameter characterize the Oberhautchen of a ventral scale.Cell outlines are not evident on the scales of G. multicarinatus. The Oberhautchen of dorsal and parietal scales of this species is prominently laminated. Laminae are less prominent on scales of the lateral fold, and no intrinsic surface structure is evident on a ventral scale. In contrast, the fossorial anguinomorph Anniella pulchra exhibits Oberhautchen surfaces with practically no intrinsic microornamentation. However, what appear to be outlines of Oberhautchen cells are visible on the dorsal and ventral scales.These observations suggest that modifications of Oberhautchen microornamentation may have evolved to reduce friction with the substrate or other scales. The lack of pronounced microornamentation of the Oberhautchen on some body scales may indicate that a complex interdigitation between clear layer and Oberhautchen cells is not essential to the sloughing process.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 223 (1995), S. 125-148 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The metamorphic species Eurycea bislineata is presented as a standard for evaluating the relationship between cranial ontogeny and life history in hemidactyliine plethodontid urodeles. Past and present descriptions are combined into a comprehensive summary of postembryonic skull development for this species, and the sequence, sizes of onset, and morphogenetic pathways are documented for all major remodelling events. Developmental series are also compared intraspecifically, between two populations of E. bislineata that differ in metamorphic size, and interspecifically, with species having different larval periods (Hemidactylium scutatum, Gyrinophilus porphyriticus, Pseudotriton ruber, E. wilderae, E. longicauda guttolineata) and with epigean (E. tynerensis, E. nana, and E. neotenes) and subterranean perennibranchiates (Haideotriton wallacei and Typhlomolge rathbuni). Cranial ontogeny is largely conserved in these hemidactyliines despite their disparate life histories. Outside the dichotomy of metamorphic and perennibranchiate development, variation is limited to interspecific differences involving the nasolacrimal duct, the repeated loss of the scleral cartilage, and minor dissociation of several metamorphic and postmetamorphic remodelling events. Some, but not all, of this variation is consistent with evolutionary differences in metamorphic size and age. The comparison of metamorphic and perennibranchiate hemidactyliines reveals a unique cranial ontogeny for urodeles, characterized by the abrupt and synchronous timing of almost all postembryonic remodelling, including the nasal skeleton, and the complete absence of these events in perennibranchiate forms. © 1995 Wiley-Liss, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 223 (1995), S. 243-261 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study examines the dosage dependency of thyroid hormone (TH)-mediated remodelling in the cranial skeleton of the hemidactyliine plethodontid urodele, Eurycea bislineata. One set of experiments quantifies morphogenetic responses in 21 tissues for four size-age classes of larvae immersed in four different T4 concentrations. A second set varies both the period and concentration of T4 treatment to evaluate the effect of different TH profiles on adult tissue shape. The tissues surveyed in this study exhibit a 100-fold range in TH sensitivity. Those in regressive morphogenesis have tissue-specific sensitivities which correlate with the timing of their remodelling in natural development: bone resorption is more sentitive than cartilage resorption and is initiated earlier in metamorphosis. In contrast, the TH sensitivities of tissues in progressive morphogenesis vary within each tissue type and even within some tissues, and they do not correlate with timing in natural development. Some explanation for this discrepancy is offered by the constant spatial and temporal relationships between nasal cartilage and dermal bone, which suggest that some TH-mediated ossification may additionally require induction by cartilage. Also, the failure of nasolacrimal duct morphogenesis at all but the lowest dosage correlates with the inductdion of integumentary changes that may preclude duct formation. Variable T4 treatments produce no effect upon the adult skull, other than loss of the nasolacrimal duct and/or foramen. These results have two developmental implicatons. First, the dosage dependencies of the nasolacrimal duct, ossification sequences, and cranial remodelling patterns all support a TH profile with exceptionally low levels at larval stages and at least a 100-fold increase at metamorphosis. Second, a small change in the rate of TH activity has the potential to effect a large-scale rearranggement and restructuring of TH-dependent remodelling. The lack of such transformations in metamorphic plethodontids suggests that TH activity is highly conserved in this group. © 1995 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 3 (1983), S. 167-184 
    ISSN: 0886-1544
    Keywords: saltatory organelle movements ; ciliary movement ; dynein ; vanadate ; microinjection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To test the idea that saltatory organelle movements of nonmuscle cells might be driven by microtubule-dynein interactions, we microinjected vanadate into several different types of cultured cell. Solutions of sodium metavanadate made up in a simple buffered salt solution were pressure microinjected into fully spread cells in an open-topped culture chamber placed on the stage of an inverted microscope. The cells were observed by oil-immersion phase-contrast optics and results were recorded on movie film. Vanadate, at 10-5-10-2 M, microinjected into cultured chick embryo fibroblasts, failed to inhibit organelle movements. To test the effectiveness of vanadate's inhibitory action under living cell conditions, ciliated epithelial cells were micro-injected. In these cells even the smallest microinjection of 5 × 10-5 M vanadate caused an immediate cessation of ciliary beating. Moreover, in cells that were well spread it was found that whereas vanadate, at 5 × 10-5 × 10-3M, inhibited ciliary motion, it failed to inhibit organelle saltations in the same cell. To determine whether vanadate would inhibit a living actin-myosin system, myocardial cells were also microinjected. Following microinjection of 5 × 10-5 and 5 × 10-4M vanadate a temporary tonic contraction (which also occurred following microinjection of buffer alone) was followed by regular beating. Taken together these results demonstrate that in living cell systems microtubule-dynein interactions are as sensitive to vanadate inhibition as they are in demembranated model systems, and that a working actin-myosin system in a living muscle cell does not share this great sensitivity. In light of the pronounced differential inhibitory effects of vanadate on the movements of cilia and organelles, our results suggest that saltatory organelle movements in chick embryo fibroblasts and rabbit oviduct epithelial cells are unlikely to be brought about by microtubule-dynein interactions.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 14 (1989), S. 3-11 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 8
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Conjugates of the single-chain ribosome-inactivating protein gelonin with ligands that bind to cell surface molecules vary greatly in their cytotoxicity. Conjugates that are not endocytosed after binding to cells exhibit low cytotoxicity similar to that of free gelonin, while conjugates that are endocytosed demonstrate enhanced cytotoxicity relative to free gelonin. However, the number of internalized gelonin molecules needed to intoxicate cells to the same degree has been found to be similar for all conjugates and for free gelonin. The intracellular concentration of gelonin has to be between 2,000-10,000 molecules/cell to achieve a surviving fraction of 0.37. Our studies revealed the presence of three distinct categories of cell surface molecules, those that are efficient in mediating endocytosis of im-munotoxins, those that are only moderately efficient, and those that seem not to cause internalization of bound immunotoxins.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 20 (1982), S. 331-336 
    ISSN: 0730-2312
    Keywords: de novo methylation of retroviral genomes ; virus expression during embryogenesis ; embryonal carcinoma cells ; maintenance methylation ; preimplantation mouse embryos ; postimplantation mouse embryos ; infectivity of retroviral genomes ; integration and methylation of retroviral genomes ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: By exposing preimplantation embryos to Moloney leukemia virus (M-MuLV), we have previously derived substrains of mice designated as Mov-1-Mov-13 which genetically transmit the virus from one generation to the next. In some of the substrains the inserted viral genome becomes activated at specific stages of embryogenesis and the available evidence suggests that these viral genomes are developmentally regulated. To investigate the effect of cellular differentiation on virus expression, M-MuLV was introduced either into preimplantation or postimplantation mouse embryos or into embryonal carcinoma (EC) cells. Whereas preimplantation embryos or EC cells are not permissive for virus expression, efficient replication occurred in postimplantation embryos or in differentiated cell lines. The viral genomes introduced into early embryonal cells were highly methylated and noninfcctious when analyzed in the adult. In contrast, viral genomes introduced into postimplantation embryos or into differentiated cells remained unmethylated and were infectious in a transfection assay. These results demonstrate an efficient de novo methylation activity which appears to be involved in repression of genes introduced into pluripotent embryonal cells and which is not observed in cells of the postimplantation embryo or in differentiated cells in tissue culture.
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  • 10
    ISSN: 0730-2312
    Keywords: colony forming cells ; differentiation ; IL-3 ; CSF1 ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: The ability of murine Steel factor to promote the in vitro production of granulocyte-macrophage progenitor cells (CFU-GM) was examined in short-term liquid cultures. Bone marrow from C57BL/6J or Sl/Sld mice was placed in culture for seven days with either Steel factor alone or in the presence of IL-3. CFU-GM responsive to GM-CSF, IL-3, and CSF-1 were measured in the input population and again after 3 or 7 days in culture. Steel factor alone increased the number of all CUF-GM types as early as 3 days after culture initiation, with further increases at day 7. This effect was protentiated by the addition of IL-3. Production of CFU-GM by C57BL/6J or Sl/Sld marrow was comparable except for enhanced production of CSF-1 responsive progenitors by Sl/Sld marrow. A recombinant Sld protein was also shown to be equivalent to the wild-type protein in its capacity to promote CFU-GM production from normal bone marrow. © 1992 Wiley-Liss, Inc.
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