meiosis

Interphase I

The phase before meiosis where chromosomes replicate. Each chromosome consists of two genetically identical sister chromatids attached at their centromeres. Homologous chromosomes undergo crossing over, exchanging genetic material at chiasmata.

Prophase I

A complex and prolonged stage where homologous chromosomes pair up through synapsis, forming tetrads. Crossing over occurs, exchanging genetic material between homologous chromatids. The nuclear envelope breaks down, and the spindle apparatus forms.

Metaphase I

Homologous chromosome pairs align at the metaphase plate. Each homologous chromosome is attached to spindle fibers from opposite poles, ensuring random orientation for genetic diversity.

Anaphase I

The spindle apparatus pulls homologous chromosomes apart toward opposite poles. Sister chromatids remain attached at their centromeres, moving as a unit.

Telophase I and Cytokinesis

The spindle apparatus continues separating homologous chromosomes. At each pole, a haploid set of chromosomes is present, though each still consists of sister chromatids. Cytokinesis divides the cell into two haploid daughter cells.

Prophase II

A new spindle apparatus forms, and chromosomes progress toward the metaphase plate. No further replication occurs before this stage.

Metaphase II

Chromosomes align at the metaphase plate, similar to mitosis, with sister chromatids facing opposite poles.

Anaphase II

The centromeres of sister chromatids finally separate, and the chromatids move to opposite poles as individual chromosomes.

Telophase II and Cytokinesis

Nuclei form at opposite poles, and cytokinesis results in four haploid daughter cells, each with unreplicated chromosomes.