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8.2.2.2. Meiosis II

Second meiotic division: equational

After meiosis I, each daughter nucleus has one of the chromosomes from each homologous pair made up of two chromatids.

The meiosis II is very similar to mitosis where the two chromatids of each chromosome separate to go to each opposite end of the spindle.

Upon completion, four cells will have formed with half as many chromosomes as the parent cell, and they also contain paternal and maternal genetic fragments by prophase I recombination.

Phases of meiosis II:


Prophase II

Very short phase in which the nuclear envelopes disintegrate, the chromosomes condense, and a new spindle is formed in each daughter cell.

Metaphase II

The chromosomes are arranged on the equatorial plate. Each one is made up of two chromatids joined by the centromere, and each one has an associated kinetochore.

Anaphase II

The centromeres are separated, and each sister chromatid (not identical) migrates to an opposite pole dragged by the fibers of the spindle of its kinetochore.

A haploid set of chromosomes with only one chromatid remains at each cell pole.

In anaphase I, homologous chromosomes separate, while in anaphase II, sister chromatids separate.

By Ali Zifan [CC BY-SA 4.0], via Wikimedia Commons

Telophase II

The nuclear envelope forms around each haploid set of chromosomes of a chromatid at each pole.

Simultaneously, cytokinesis occurs, with which four cells with half the number of chromosomes (haploid) will form, and which, in addition, contain alternating paternal and maternal segments, since some of their chromosomes are recombined.

By Ali Zifan [CC BY-SA 4.0], via Wikimedia Commons