ISSN:
0003-276X
Schlagwort(e):
Life and Medical Sciences
;
Cell & Developmental Biology
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Medizin
Notizen:
Human embryonic hand and foot plates (horizon XVI) exhibit localized differences in mitotic activity between developing digital and interdigital zones of mesenchyme. To investigate development of regulation of cell reproduction, mesenchymal cells from lower limb buds dissected from a human embryo (stage XV) were cultured. Electron microscopy reveals that HLM15 cells in situ are fibroblastic, exhibit euchromatic nuclei, one to two peripheral nucleoli, extensive granular ER, free ribosomes, and microfilaments and microtubules oriented in the long axis of cellular processes. Cells released from substratum with trypsin-EDTA become rounded and microfilaments and microtubules become disoriented, perinuclear bundles. HLM15 has a mean generation time of 24 hours during logarithmic growth and karyotype analysis indicates that cells retain diploid chromosomal number after 17 passages. DNA-fluorochrome analysis on the Los Alamos Flow Microfluorometer (FMF) demonstrates that HLM15 cells possess no detectable polyploidy. Computer fit of FMF distributions reveal that random populations of HLM15 during exponential growth contain 42.6% cells in G1, 45.9% in S and 11.5% in G2+M. As confluency is reached these data become 57.6%, 37.5% and 4.9% respectively. Disaggregated limb mesenchyme (in vivo) analyzed without culturing exhibit FMF distributions of 56.1% in G1, 36.7% in S and 7.2% in G2+M. Similarities in cell cycles between near-confluent HLM15 cultures and limb mesenchyme in vivo suggest that regulation can be achieved by increasing or decreasing the traverse time through G1 (both in vitro and in vivo). The proportion of non-cycling cells (G0) in the FMF G1 distribution is presently not known.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/ar.1091750403
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