Stages of Prophase

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

prophase one