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Journal of Cell Science, Vol 3, 295-308, Copyright © 1968 by Company of Biologists
Submitted on August 23, 1967
1 Department of Biology, Guy's Hospital Medical School London, S.E. 1
Observations of the microtubular km system and filamentous M systems in living specimens of Stentor coeruleus show that on contraction of the body both systems shorten, thicken and remain straight, but that on initial relaxation they behave differently: the km fibres begin to lengthen later than the M fibres, the latter being thrown into sinuous folds. Electron microscopy of specimens cooled before fixation appears to confirm this difference in behaviour in relaxing specimens.
The M fibres of the stalk region are discrete and prominent bundles, but in the adoral half of the body they are extensively linked together by side branches. There are diffuse filamentous attachments between the M fibres and the kinetosomes.
The vertical microtubular stacks which make up the km fibres are each linked with a pair of kinetosomes. Each stack contains about 21 microtubules grouped in a 2 + 19 pattern. Cross-bridges are present between the microtubules of adjacent stacks. The number of stacks in each km fibre cross-section is smaller in extended specimens than in contracted ones, indicating that the stacks slide upon one another as the body changes its length.
Submitted on August 23, 1967
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E. Newman Contraction in Stentor coeruleus: A Cinematic Analysis Science, August 4, 1972; 177(4047): 447 - 449. [Abstract] [PDF] |
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