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Physiology and the whole organism  ·  Article

Mitotic spindle, asters and the centrosome

The mitotic figure is the visible apparatus of cell division. A centrosome sits at each pole, surrounded by radiating asters, and a spindle of fibres runs between them across the nuclear region.7 Early authors argued over where the centrosome belongs and how continuous the fibres are with the rest of the cell.13 Later writers used the figure as a marker of division.9

Earliest held
1894, Bateson, W.
Most discussed in
The Cell in Development and Inheritance, 1896
In the library
409 passages in 15 works
Rewritten
2026-10-06
18501875190019251950197520002025Wilson, E. B., 18961Wilson, E. B., 18962Verworn, M., 18993Verworn, M., 18994Loeb, J., 19165Crile, G. W., 19266Thompson, D. A. W., 19927Chifflet S, Hernández JA, 20128Volodyaev I, Beloussov LV, 20159
01

Descriptions of the figure

Verworn (1899) described the sequence in a dividing nucleus. The chromatic threads split lengthwise and the nuclear membrane dissolves. The centrosomes then become visible at opposite poles, surrounded by protoplasmic radiations, and a spindle-shaped fibrous figure joins them.4 Thompson's later account of the stages follows Wilson. Each centrosome is ringed by an aster and a clear centrosphere, and the spindle stretches between the two. The chromosomes line up midway between the poles.7 After division the spindle fibres disappear, and the centrosome usually remains outside the nucleus.

02

Disputed structure

Wilson (1896) reported that the facts in some cases turned on whether astral rays reach the central granule. Kostanecki and Siedlecki asserted this for Ascaris, and Fürst denied it.1 Wilson also surveyed observers who saw astral fibres join the general cell meshwork. Rabl proposed that spindle fibres and astral rays keep their identity in the resting cell and stay centred on the centrosome.2 Verworn recorded a second dispute. Many, led by van Beneden, treated the centrosome as a specific cell constituent. Hertwig held that it belongs to the nucleus and enters the protoplasm during fertilisation.3

03

Transitory organ, electrical view

Loeb (1916) noted that certain eggs held centrosomes and astrospheres at division and yet returned to rest. He concluded that centrosomes are transitory organs, active only under certain conditions.5 He left open whether body cells change from rest to activity in the same way. Crile (1926) took up a different question, whether cell division is an electrical process. He listed the objections raised against that idea. One was that the elaborate look of mitotic figures had encouraged equally elaborate descriptions of the processes behind them.6

04

Later uses and limits

Mitotic figures also served as a count of dividing cells. In Gurwitsch's onion root experiment, one root tip was aimed at the division zone of another. Counting mitotic figures, the exposed side showed a significantly higher proportion of cells in mitosis. This was called the mitogenetic effect, as Volodyaev and Beloussov (2015) recount.9 Chifflet and Hernández (2012) add a limit to the centrosome's role. In fibroblast-like cells centrosomes nucleate and organise microtubules. In epithelial cells most microtubules are acentrosomal.8

SourcesEach quotation was checked word for word against the passage it opens.
  1. The matter of fact turns largely on the question whether the astral rays traverse the larger sphere to the central granule.Wilson, E. B., 1896 · The Cell in Development and Inheritance · open at passage 740
  2. Rabl ('89, 2) suggested that neither spindle-fibres nor astral rays really lose their identity in the resting cell, being only modified in formWilson, E. B., 1896 · The Cell in Development and Inheritance · open at passage 752
  3. O. Hertwig ('92) upholds the view that it belongs to the nucleus as a part of the nuclear substance, and passes from it into the protoplasm only during the activity of the former in fertilisationVerworn, M., 1899 · General Physiology: An Outline of the Science of Life · open at passage 203
  4. at the two opposite poles of the nuclear mass the centrosomes, or central bodies (p. 69), surrounded by their protoplasmic radiations, now become visibleVerworn, M., 1899 · General Physiology: An Outline of the Science of Life · open at passage 524
  5. the centrosomes are only transitory organs or organs which are only active under certain conditionsLoeb, J., 1916 · The Organism as a Whole, from a Physicochemical Viewpoint · open at passage 304
  6. Many other objections to the conception that the processes of cell division are electrical processes have been advanced.Crile, G. W., 1926 · A Bipolar Theory of Living Processes · open at passage 299
  7. Between the two centrosomes with their asters stretches a bundle of achromatic fibres, the spindle.Thompson, D. A. W., 1992 · On Growth and Form · open at passage 406
  8. Unlike fibroblastic-like cells, where centrosomes are responsible for the nucleation and organization of microtubules, in epithelial cells, most microtubules are acentrosomal.Chifflet S, Hernández JA, 2012 · The plasma membrane potential and the organization of the actin cytoskeleton of… · open at passage 4
  9. The exposed side possessed significantly higher proportion of cells in mitosis than the non-exposed sideVolodyaev I, Beloussov LV, 2015 · Revisiting the mitogenetic effect of ultra-weak photon emission · open at passage 3
Linked ideas
Gurwitsch's onion root experiment used counts of mitotic figures to show a higher rate of division on the exposed side.
Chifflet and Hernández link membrane potential to cytoskeleton organisation, including microtubule arrangements that are acentrosomal in epithelia.
Polarityrelated to
The two poles of the spindle, each with a centrosome and aster, give division an axis.
Cell division and inheritance in Wilson's account link the dividing figure to questions of how the cell's parts are passed on.
Vitalism and mechanismin tension with
Loeb's physicochemical reading of the centrosome as a transitory organ contrasts with more elaborate descriptive readings of the mitotic figure.
Where it is discussedPassages matching aster, astral rays, mitotic figure, spindle fibres
1896The Cell in Development and Inheritance · Wilson, E. B.341
1992On Growth and Form · Thompson, D. A. W.22
1899General Physiology: An Outline of the Science of Life · Verworn, M.19
1930The History of Biological Theories · Rádl, E.5
1926A Bipolar Theory of Living Processes · Crile, G. W.4
1901Regeneration · Morgan, T. H.3
1916The Organism as a Whole, from a Physicochemical Viewpoint · Loeb, J.3
1894Materials for the Study of Variation Treated with Especial Regard to… · Bateson, W.3
2015Revisiting the mitogenetic effect of ultra-weak photon emission · Volodyaev I, Beloussov LV2
1912The Mechanistic Conception of Life · Loeb, J.2