Most of the events that function to differentiate meiosis from mitosis occur in Prophase I
- Homologous chromosomes form bivalents (or tetrads) and crossing over occurs between non-sister chromatids
Prophase I is divided into 5 distinctive sub-stages:
- Leptotene – The chromosomes begin to condense and are attached to the nuclear membrane via their telomeres
- Zygotene – Synapsis begins with a synaptonemal complex forming between homologous chromosomes
- Pachytene – Crossing over of genetic material occurs between non-sister chromatids
- Diplotene – Synapsis ends with disappearance of synaptonemal complex; homologous pairs remain attached at chiasmata
- Diakinesis – Chromosomes become fully condensed and nuclear membrane disintegrates prior to metaphase I
Stages of Prophase I
