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Question
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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Solution
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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RELATED QUESTIONS
The following is the illustration of the sequence of ovarian events (a − i) in a human female
(i) Identify the figure that illustrates ovulation and mention the stage of oogenesis it represents.
(ii) Name the ovarian hormone and the pituitary hormone that have caused the above mentioned event.
(iii) Explain the changes that occur in the uterus simultaneously in anticipation.
(iv) Write the difference between ‘c’ and ‘h’.
(v) Draw a labeled sketch of the structure of a human ovum prior to fertilization.
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Give scientific reason.
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(A) - Head of the sperm consists of acrosome and mitochondria.
(R) - Acrosome contains spiral rows of mitochondria.
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Gray crescent is the area ______.
The head of the epididymis at the head of the testis is called ______.
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Select the correct sequence of stages of spermatogenesis in a human male ______.
