REPRODUCTION
HUMAN REPRODUCTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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prophase I
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metaphase II
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metaphase I
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prophase II
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anaphase I
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Detailed explanation-1: -At birth the ovary contains about 1 to 2 million primary oocytes. The first stage of meiosis starts during fetal development but is arrested in the late stage of prophase I until puberty, which usually occurs between ages 10 and 14 in females.
Detailed explanation-2: -The creation of oogonia Meiosis begins with DNA replication and meiotic crossing over. It then stops in early prophase.
Detailed explanation-3: -During a womans ovarian cycle one oocyte is selected to complete meiosis I to form a secondary oocyte (1N, 2C) and a first polar body. After ovulation the oocyte is arrested in metaphase of meiosis II until fertilization.
Detailed explanation-4: -In female mammals, meiosis of oocytes starts before birth and sustains at the dictyate stage of meiotic prophase I before gonadotropins-induced ovulation happens. Once meiosis gets started, the oocytes undergo the leptotene, zygotene, and pachytene stages, and then arrest at the dictyate stage.