pachytene stage

biology

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July 1, 2026

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The pachytene stage is a phase within prophase I of meiosis. During this stage, chromosomes thicken and become visible, each consisting of two sister chromatids. Homologous chromosomes pair up, forming structures called tetrads or bivalents, which contain four chromatids in total. A crucial event that occurs during the pachytene stage is crossing-over, where homologous chromosomes exchange genetic material. This exchange is vital for genetic diversity. The pachytene stage follows the zygotene stage and precedes the diplotene stage of meiotic prophase I.12

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heredity
During meiosis
At pachytene they pair, the corresponding portions of the two chromosomes lying side by side. The chromosomes then duplicate and contract into paired chromatids. At this stage the pair of chromosomes is known as a tetrad, as it consists of four chromatids. Also at this stage…
Read More
At pachytene they pair, the corresponding portions of the two chromosomes lying side by side. The chromosomes then duplicate and contract into paired chromatids. At this stage the pair of chromosomes is known as a tetrad, as it consists of four chromatids. Also at this stage…
Read More