ISSN:
1615-6102
Schlagwort(e):
Morphometry
;
Life cycle
;
Chondriome
;
Nucleus
;
Leucoplast
;
Polytoma
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Summary Quantitative electron microscopy of serial sections was used to study thePolytoma papillatum cell and some of its constituents (nucleus, chondriome, leucoplast) during its vegetative life cycle. The volumes of cells just entering into or passing through mitosis varied considerably and seemed to determine the number of subsequent division processes. Whereas a volumetric balance existed between the cell (100%) and the chondriome (8–9%) during the whole life cycle, there was a correlation between cell and nuclear volumes (8–10%) only during interphase growth and the onset of mitosis. At telophase the nucleus-to-cell-volume ratio was reduced to 2%, but gradually increased during cytokinesis (4.6% at early cytokinesis; 6.5% at late cytokinesis) until it reached the initial value again in newly formed daughter cells. The leucoplast-to-cell-volume ratio (10–26%) varied considerably without any recognizable dependence upon cell cycling. The mean short axis of mitochondrial profiles was proportional to the mean diameter (=thickness) of the mitochondria; the specific surface (outer membrane area per 100 μm3 mitochondrial volume), and the surface-to-volume ratio changed rhythmically. Changes in mitochondrial surface-to-volume ratio (Sc/Vc) were apparently correlated with changes in mitochondrial diameter (Dc). This relationship can be approximately described by the function Sc/Vc=4/Dc. Deviations of the surface-to-volume ratios of the nuclei from the surface-to-volume ratios of idealized spheres of equal size, indicating profound changes in nuclear shape, were found mainly during mitosis. Results were compared with those obtained from other morphometric investigations and discussed with regard to their functional meaning.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01283321
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