2. Meiosis and its Phases

Division II—Equational division

The chromosome number stays the same, the cells replicate and result in four cells. The events closely resemble the events in mitosis, except that there is no duplication of DNA during the interphase that may or may not occur between the two divisions.

Prophase II—Main features

  • Chromosomes of both nuclei become shorter and thicker. The two-stranded nature becomes apparent once again.

Metaphase II—Main features

  • Chromosomes align their centromeres along the equator.
  • Spindle fibers form and attach to each centromere, extending from one pole to the other.

Anaphase II—Main features

  • The centromeres and chromatids of each chromosome separate and begin their migration to the opposite poles.

Telophase II—Main features

  • The coils of chromatids—now called chromosomes again—relax and the chromosomes become longer and thinner.
  • Nuclear envelopes and nucleoli reform for each group of chromosomes.
  • New cell walls form between the four groups of chromosomes.
  • Each set of chromosomes in the four new cells has exactly half of the chromosome number of the original number.

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