Meiosis — Cell Division
The mother cell's nucleus breaks down and spindle fibres form from two poles to pull the chromosomes apart. First the mother cell divides into two cells with the same number of chromosomes as the mother. Each of these two cells then divides again — new spindle fibres form once more — producing four daughter cells, each with half the number of chromosomes and its own newly formed nucleus.
Stage 1 of 5: Interphase — Mother Cell (2n = 4)
Duplicated chromosome
Single chromosome
Nuclear envelope
Spindle fibre
Centrosome (spindle pole)
Summary: Meiosis is a two-step nuclear division. Before it begins, the DNA is copied
so every chromosome consists of two sister chromatids. In the first division the nuclear
envelope breaks down, spindle fibres grow out from two poles and pull whole chromosomes
apart — forming two cells that still carry the same chromosome count as the mother, each
with its own reformed nucleus. In the second division, spindle fibres form again inside
each of those two cells and pull the sister chromatids apart — producing four daughter
cells in total, each with only half the chromosome number of the mother cell and a nucleus
of its own. This halving is essential for sexual reproduction, so that when two sex cells
combine, the full chromosome number is restored in the offspring.