- Chromatin condenses and supercoils so chromosomes shorten and thicken.
- Chromosomes come together in their homologous pairs to form a bivalent.
- The non-sister chromatids wrap around each other and attach at chiasmata. Sections may be swapped in crossing over.
- Nucleolus disappears and nuclear envelope disintegrates.
- A spindle (made of microtubules) forms.
- Bivalents line up across equator of spindle, attached to spindle fibres at the centromeres.
- They are arranged randomly with each member of a homologous pair facing opposite poles.
- The homologous chromosomes in each bivalent are pulled by the spindle fibres to opposite poles. The centromeres do not divide. The chiasmata separate (and swapped sections stay swapped).
- In animals two new nuclear envelopes form and the cell divides by cytokinesis.
Meiosis 2 (division is in a plane at right angles to meiosis 1)
- Reformed nuclear envelopes break down, the nucleolus disappears, chromosomes condense and spindles form.
- Chromosomes line up on equator of spindle and are attached to the spindle fibres at centromeres.
- The chromatids of each chromosome are randomly assorted.
- The centromeres dvide and the chromatids are pulled to opposite poles by the spindle fibres. The chromatids randomly segregate.
- Nuclear envelopes reform around the haploid daughter nuclei
- In animals the two cells now divide to give four haploid cells
- In plants a tetrad of four haploid cells is formed.