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  • 1
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The technique of buoyant density separation in gradients of Bovine Serum Albumin has been used to separate hemopoietic cell populations in mouse bone marrow that form in vivo spleen colonies and in vitro colonies of granulocytes and macrophages in an agar culture system. The density distribution profiles showed a number of reproducible density subpopulations of both in vivo and in vitro colony forming cells (C.F.C.'s). The mean density of in vitro C.F.C.'s exceeded that of the in vivo but overlap of the density profiles of the two populations was evident. Density-related differences in seeding efficiency of in vivo C.F.C.'s were observed.Freund's adjuvant treatment increased marrow and spleen in vitro C.F.C. populations. Marrow density profiles obtained three and seven days after adjuvant showed a progressive increase in in vitro C.F.C.'s in a restricted density region with no associated elevation of in vivo activity.The antimitotic agent, vinblastine, revealed differences in mitotic activity between the two cell populations, reducing the in vitro C.F.C. population to .07% and the in vivo to 5% of normal in 24 hours. Density separation of vinblastine-treated marrow produced density regions devoid of in vitro activity but containing in vivo in vivo C.F.C.'s which, upon transfer to irradiated recipients, regenerated both in vivo and in vitro density distribution profiles.
    Additional Material: 8 Ill.
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  • 2
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The technique of buoyant density separation in gradients of Bovine Serum Albumin has been used to separate in vivo and in vitro colony forming cells (C.F.C.'s) in hemopoietic tissue of mouse fetal liver. Differences in the density distribution profiles showed that the in vivo and in vitro C.F.C.'s were different cell populations but the existence of an “out-of-phase” density association suggested that the two cell types were closely related.Complex density heterogeneity of both cell populations was observed at later stages of liver development and was similar to that seen in adult marrow. A homogeneous population of in vivo and in vitro C.F.C.'s occupied a very light density position in 10.5 day fetal liver. The subsequent development of density heterogeneity was associated with progressive acquisition of higher density subpopulations. Transfer experiments showed the capacity of the lightest density cells from the earliest stage of liver hemopoiesis, to generate higher density colony forming cells in the environment of the adult marrow. Density determined differences in seeding efficiency of in vivo C.F.C.'s were observed but no evidence was obtained for differences in either in vivo or in vitro colony morphology in different density subpopulations.
    Additional Material: 4 Ill.
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  • 3
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mouse bone marrow cells were separated by adherence column and albumin density gradient procedures, assaying for spleen colony forming units (in vivo CFU's), agar colony forming cells (in vitro CFC's) and cluster forming cells. Column filtrates were enriched for CFU's whereas in vitro CFC's and cluster-forming cells were enriched in adherent fractions. Gradient separation of these column fractions gave density distribution profiles indicating the non-identity and heterogeneity of CFU's and in vitro CFC's.
    Additional Material: 4 Ill.
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  • 4
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Hemopoietic colony formation in agar occurred spontaneously in mass cultures of marrow cells obtained from a number of species (guinea pig, rat, lamb, rabbit, pig, calf, human and Rhesus monkey). This contrasted with the observation that colony formation by mouse bone marrow exhibited an absolute requirement for an exogenous source of a colony stimulating factor. Analysis of spontaneous colony formation in Rhesus monkey marrow cultures revealed the presence of a cell type in hemopoietic tissue, capable of elaborating colony stimulating factor when used to condition media or as feeder layers. Equilibrium density gradient centrifugation separated colony stimulating cells from in vitro colony forming cells in monkey bone marrow. Separation studies on spleen, blood and marrow characterized the stimulating cells as of intermediate density, depleted or absent in fractions enriched for cells of the granulocytic series and localized in regions containing lymphocytes and monocytes. Adherence column separation of peripheral blood leukocytes showed the stimulating cells to be actively adherent, unlike the majority of lymphocytes, and combined adherence column and density separation indicated that stimulating cells were present in hemopoietic tissue within the population of adherent lymphocytes or monocytes.
    Additional Material: 6 Ill.
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  • 5
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Buoyant density gradient separation of Rhesus monkey bone marrow, spleen and blood leukocytes has demonstrated a reproducible and homogeneous light density distribution profile of cells capable of forming hemopoietic colonies in agar culture (in vitro colony forming cells  -  CFC). High resolution density gradient separation performed on a light density fraction of bone marrow produced on average a 100-fold enrichment of in vitro CFC with the most enriched fractions containing the majority of the in vitro CFC population present in the original marrow. Fractions were routinely obtained in which up to 23% of cells formed colonies and 33% were capable of proliferating to some degree upon stimulation. Tritiated thymidine suiciding showed the active proliferative status of the in vitro CFC and application of autoradiography and morphological characterisation to highly enriched density fractions has shown that the in vitro CFC in normal marrow is a transitional lymphocyte. Single cell transfer experiments have shown that in vitro CFC's formed colonies containing both granulocytes and macrophages, formally demonstrating the clonal origin of in vitro colonies and the common origin of granulocytes and macrophages.
    Additional Material: 4 Ill.
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