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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 125 (1985), S. 127-134 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Methylcellulose cultures containing mouse marrow cells at low densities and partially purified preparations of erythropoietin and Interleukin-3 were scored after 2 weeks for the presence of macroscopic multilineage colonies (from “primary” CFU-macro GEMM). Whole cultures were then harvested and replated to assess the number of “secondary” CFU-macro GEMM produced, but not detected, during the primary culture period. In such experiments adherent marrow cells yielded significantly higher numbers of secondary CFU-macro GEMM than did either fresh or nonadherent marrow cells. Removal of macroscopic colonies prior to replating showed that most secondary CFU-macro GEMM were not derived from primary CFU-macro GEMM. In vivo studies also revealed a differential effect of adherence separation on the frequency of day 10 CFU-S, which decreased, by comparison to cells capable of long-term repopulation, which increased. Primary adherent CFU-macro GEMM from 5-fluorouracil (5-FU) treated mice showed an 18-fold higher self-renewal capacity than their counterparts in normal marrow. Nevertheless the majority of secondary CFU-macro GEMM obtained from primary cultures of adherent 5-FU cells were again not derived from primary CFU-macro GEMM. Cells capable of immediately generating large multilineage colonies thus appear to represent an intermediate compartment of pluripotent progenitors whose self-renewal properties, may, however, vary over a considerable range. Our results further suggest that these progenitors are derived ultimately from a more primitive adherent cell whose tendency to begin to divide in vitro is low and whose presence correlates with cells capable of long-term myeloid repopulation in vivo.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The placental membranes of the four-eyed opossum were studied by light and electron microscopy. The individual fetuses in each uterus were surrounded by amnion, had allantoic sacs of approximately the same size as each fetus, and were situated in a common yolk sac cavity. The extent of the choriovitelline placenta was marked by a prominent sinus terminalis, and at this margin there was a region where the trophoblast cells penetrated folds of the endometrium. Elsewhere the choriovitelline placenta was closely applied to the uterine epithelium along most of its surface, but the microvilli of the two epithelia did not interdigitate. Numerous inclusion bodies were seen in the trophoblast of both the choriovitelline and bilaminar omphalopleure portions of the placenta, but the aggregates were larger in the latter. The endoderm cells of the choriovitelline placenta had extensive endoplasmic reticulum and numerous mitochondria, but did not have conspicuous absorption canaliculi.Placentation in the four-eyed opossum appears to represent a progressive advance over that of the Virginia opossum both in confluence of the yolk sacs of the fetuses and in having a region of penetration of the maternal endometrium by trophoblast.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The chorioallantoic placenta of the bat (Myotis lucifugus) is hemodichorial and has an ectoplasmic layer and an intrasyncytial lamina interposed between the maternal blood space and the underlying endoplasmic portion of the syncytial trophoblast. The barrier and/or transport function of the trophoblast of this species was investigated. When Thorotrast was injected into the maternal vascular system, only small amounts appeared in the trophoblast, and it could not be demonstrated deep to the syncytial trophoblast.Injected peroxidase and ferritin were both rapidly taken up by the trophoblast, these tracers being found in coated vesicles and tubules, in multivesicular bodies, and in dense bodies. Peroxidase was transported across the trophoblast and could be found in macrophages in the fetal connective tissue and in vesicles in the fetal endothelium. Since ferritin is present in the cytotrophoblast, macrophages and fetal endothelium in uninjected as well as injected animals, the exogenous material could not be followed beyond the syncytium. In addition to demonstrating the cytological pathway by which absorbed proteins cross the trophoblast of the chorioallantoic placenta of the bat, the results of this study suggest that the labyrinth in this species should be considered a possible route for passage of endogenous proteins to the fetus.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 167 (1970), S. 231-251 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Cytological investigation of Hofbauer cells in various stages of gestation reveals that they are similar to normal macrophages except for unusually large cytoplasmic flanges and included vacuoles. The system of vacuoles is apparently the result of macropinocytotic activity. The individual vacuoles undergo asymmetrical collapse in regions adjacent to small juxtavacuolar tubules thought to be derived from the agranular endoplasmic reticulum. In addition, coated micropinocytotic vesicles are common. Hofbauer cells thus appear to be a type of macrophage with an unusual capacity for fluid ingestion. In younger placentas, Hofbauer cells are usually associated with extracellular compartments within the stroma. These compartments are relatively free of collagen fibrils and demonstrable ground substance and are clearly demarcated from the rest of the stroma by processes of fibroblasts. The abundance of these cells in early placentas, their location in the stroma, and evidence of their pinocytotic activity suggest that these cells may play a role in removal of proteins from interstitial fluid. Hofbauer-like cells were also studied in the guinea pig and the little brown bat. Of these two species, the Hofbauer-like cells of the bat more closely resemble human Hofbauer cells in that they show evidence of extensive macropinocytotic activity.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    The @Anatomical Record 175 (1973), S. 539-559 
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The protein tracers, horseradish peroxidase and ferritin, are demonstrable in the subzonal space of all preimplantation stages within ten minutes when incubated in vivo or in vitro. However, there is very little uptake of these proteins by ova and two-cell stages. By the blastocyst stage there is greatly increased uptake of exogenous protein. The proteins appear in coated micropinocytotic vesicles and tubules, larger vacuoles, and more complex bodies. Blastocysts from the period of lactationally delayed implantation show an even greater amount of uptake, especially in the supranuclear region. Peroxidase reaction product can be demonstrated in the cavity of day 5 blastocysts in 30 minutes, and in the cavity and basal lamina of the blastocysts during delayed implantation in ten minutes. Ferritin was more sparsely distributed, and was not seen in the blastocyst cavity in any of the time periods. Peroxidase is apparently transported via an intracellular pathway, since it is not seen in the elaborate intercellular spaces between trophoblast cells. Acid phosphatase activity is demonstrable in vacuoles, dense bodies and Golgi cisternae in all stages, indicating that the potential for degradation of ooplasm and phagocytized material by a lysosomal system is present in all of the preimplantation stages examined.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: A study of the uptake of exogenous proteins, peroxidase, ferritin, and myoglobin by rabbit blastomeres of different developmental stages was undertaken to determine some of the means by which these stages ingest protein. Exposure of embryos in preimplantation stages, ranging from fertilized ovum to late blastocyst, was carried out in vitro with selected in vivo controls. Blastomeres of early cleavage stages up to the morula show little uptake of peroxidase. However, the endocytosis of peroxidase greatly increases with the morula stages and continues at an elevated level through the blastocyst stages. The uptake of the tracer is initially accomplished via micropinocytotic vesicles and tubules and can have several subsequent fates. The tracer can pass into larger vacuoles and be transported into the cavity of the blastocyst, or can pass into multivesicular bodies where it is presumably degraded by the lysosomal system for cellular use. The use of myoglobin at selected blastocyst stages yielded results similar to those obtained with peroxidase. However, the response by the blastomeres to ferritin is different. Endocytosis of ferritin is scant at all preimplantation stages, even though the ferritin has no difficulty reaching the surface of the blastomeres. The experiment with mechanically denuded blastocysts indicated that ferritin did not adsorb to the cell surface.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 0003-276X
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: Splitting the uterus longitudinally through implantation sites makes it possible to obtain access to blastocysts and implantation chambers during stages of implantation of the blastocyst in the rat. On the afternoon of day 5 of pregnancy, blastocysts lie in a shallow antimesometrial depression and tend to fall free of the uterus when the chamber is opened. On day 6, blastocysts are oriented in a mesometrial-antimesometrial plane, occupy a distinct implantation chamber, and tend to adhere to one side or the other of the uterus, leaving an imprint on the contralateral side. After about noon of day 6, some of the blastocysts split in half laterally, and by day 7 all blastocysts which are exposed are split. In addition to demonstrating increased adhesion of blastocyst to uterine epithelium, the procedure clearly shows the progressive elongation of the implantation chamber. The embryonic cell mass is specifically oriented on day 6, and is clasped but not distorted, whereas the abembryonic trophoblast is slightly compressed and indented by the uterine epithelium. The microvilli of the uterine epithelium within the imprint become progressively flattened when compared to the microvilli of the implantation chamber outside of the imprint. The method provides a means of gaining direct access to the surface of uterine epithelium precisely where it has been in association with the blastocyst not only for scanning electron microscopy but also for studies of the properties of the surface constituents.
    Type of Medium: Electronic Resource
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