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The appearance of the macronucleus depends on the stage of the cell,
whether the cell is in early, middle or late growth phase or is in
stationary phase or whether the cell is dividing by mitosis or is
undergoing meiosis. In interphase the major changes will be observed
in the nucleoli as the chromatin bodies maintain a relatively constant
appearance. The nucleoli often exhibit a regular beaded appearance
(arrows) on the surface which is seen as regularly spaced
threads (arrowheads) when the nucleolus is sectioned through
its surface. Presumably these represent stages in ribosomal subunit
development prior to the separation of individual subunits for
transport through the nuclear pores to the cytosol. EM taken on
1/10/73 by R. Allen with Hitachi HU11A TEM. Neg. 16,900X. Bar =
0.25µm.
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