Electron microscopy of sections of hypoton pretreated human metaphase chromosomes reveal irregular and multiple folded fibrils ca. 200–250 Å thick. After staining with uranyl acetate the central core of the fibrils is contrasted, whereas after treatment with phosphor tungsten acid the periphery is stained. The fibril appears to be thickened due to the hypotonic pretreatment.
The most propable interpretation seems to be, that one fibril, made up of a DNA double helix and a histon-frame, is laid into many irregular minor foldings building up a strand corresponding to a chromatid. In metaphase this strand is laid into major coils.
ZusammenfassungDünnschnitte von hypoton vorbehandelten Metaphase-Chromosomen des Menschen zeigen im Elektronenmikroskop unregelmäßig und vielfach gefaltete Fibrillen von ca. 200–250 Å Durchmesser. Nach Uranylacetatkontrastierung ist vorwiegend das Zentrum der Fibrillen dargestellt, während nach Phosphorwolframsäurebehandlung die Peripherie kontrastiert ist. Die Fibrillen erscheinen durch die hypotone Vorbehandlung wahrscheinlich verdickt.
Als wahrscheinlichste Deutung der Bilder wird angenommen, daß eine Fibrille, die aus einem DNS-Doppelschraubenmolekül mit einem Histongerüst besteht, in viele kleine Falten und Schlingen gelegt, einen dickeren Strang, der einem chromatid entspricht, aufbaut. In der Metaphase ist dieser Strang noch zusätzlich in große Windungen gelegt.
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Anatomisches Institut der Justus Liebig-Universität Gießen, Lehrstuhl II, Gie Ben, Deutschland
H. G. Schwarzacher
Histologisch-Embryologisches Institut der Universität Wien, Wien, Österreich
W. Schnedl
Schwarzacher, H.G., Schnedl, W. Zur Ultrastruktur der Chromosomen des Menschen. Hum Genet 8, 75–80 (1969). https://doi.org/10.1007/BF00295829
Received: 08 June 1969
Issue Date: June 1969
DOI: https://doi.org/10.1007/BF00295829
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