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प्रश्न
Explain the development of a secondary oocyte (ovum) in a human female from the embryonic stage upto its ovulation. Name the hormones involved in this process.
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उत्तर
Oogenesis
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The ovum (egg) is formed by the process of oogenesis.
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It starts during embryonic growth with millions of gamete mother cells (oogonia) forming in the foetal ovary.
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These cells undergo meiosis, but get temporarily arrested at the prophase and are called primary oocytes.
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Before reaching puberty, a large number of primary oocytes degenerate and the remaining ones get surrounded by layers of granulosa cells and new theca and are called secondary follicles.
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The secondary follicles are then converted into tertiary follicles that have a fluid-filled cavity called the antrum. At this stage, the primary oocyte present within the tertiary follicle completes meiosis, which results in the formation of haploid secondary oocyte and a tiny polar body.
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This tertiary follicle further changes into the Graafian follicle. The secondary oocyte is surrounded by the zona pellucida.
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Then the Graafian follicle ruptures to release the ovum by ovulation.
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| List - I | List - II |
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| B. Middle piece | II. Sperm motility |
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| D. Tail | IV. Genetic material |
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