What occurs during the first stage of meiosis?
Meiosis consists of meiosis I and meiosis II. Both meiosis I and Meiosis II are further divided into prophase, metapahse, anaphase and telophase.
Prophase of meiosis I is the first stage of meiosis.
Pairing of homologous chromosomes occurs in early prophase. Prophase I is further sub-divided into sub-stages like leptotene, zygotene, pachytene, diplotene and diakinesis.
Pairing of homologous chromosomes occur during pachytene stage. It is followed by shortening and thickening of chromosomes. Crossing over occurs during pachytene stage.
The site of crossing over becomes visible in the form of chiasma formation in diplotene stage.
The bivalents with specific shape are formed during diakinesis, depending on the number and position of crossing over.