2. Zygotene or zygonema or yolked threaded stage: Zygonema (Zygo = paired, nema = thread)
Homologous chromosomes coming from two parents begin to pair lengthwise (It is called synapsis). The pair is now referred to as bivalents. Each bivalent is formed of one paternal and one maternal chromosome. Under electron microscope, a filamentous ladder like nucleoproteinous complex, called synaptonemal are seen. Synaptonemal complex is seen between the homologous chromosomes.
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The centriole divides into two daughter centrioles, which migrate to the opposite poles of the cell.
