Protoplasma

, Volume 101, Issue 1–2, pp 37–46 | Cite as

Nuclear division in the cyst, and white spot nuclei preceding cyst formation, inAcetabularia wettsteinii

  • M. B. E. Godward
  • K. Beth
  • J. Pacey
Article

Summary

Electron microscopy of nuclear division in young cysts ofAcetabularia wettsteinii shows that the dividing nucleus hat two additional cisternae of endoplasmic reticulum immediately outside the nuclear envelope. These additional cisternae are attached to, and apparently formed from a membrane body which develops outside the nucleus in early prophase. The interphase nucleus does not have the additional cisternae. The nucleoli are extruded from the nucleus at anaphase, the nucleolar bodies remaining in the peri-nuclear cytoplasm. The chromosomes have localized centromeres; the stratified ultrastructure characteristic of some chlorophycean and animal kinetochores has not been found inAcetabularia, although the kinetochore appears distinct, projecting from the chromatid, and has attached microtubules. The “condensed bodies” of the white spot nucleus are discussed.

Keywords

Acetabularia Mitosis Nucleolus Perinuclear envelopes 

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Copyright information

© Springer-Verlag 1979

Authors and Affiliations

  • M. B. E. Godward
    • 1
    • 2
    • 3
  • K. Beth
    • 1
    • 2
    • 3
  • J. Pacey
    • 1
    • 2
    • 3
  1. 1.Department of Plant Biology and MicrobiologyQueen Mary CollegeLondonEngland
  2. 2.Stazione ZoologicaNaplesItaly
  3. 3.Department of BiologyQueen Elizabeth CollegeLondonEngland

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