Human Fertilization: Stages and Changes
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Questions and Answers

What is the primary function of the zona pellucida?

  • To act as a barrier against multiple sperm (correct)
  • To assist in the cleavage divisions
  • To aid in sperm motility
  • To provide nutrients to the oocyte
  • What role do cortical granules play after sperm interaction with the oocyte?

  • They enhance oocyte nutrition during development
  • They contribute to the formation of the tail of the sperm
  • They initiate cortical reaction to prevent multiple fertilizations (correct)
  • They are involved in the cleavage stages of the zygote
  • Which of the following statements about the sperm structure is NOT correct?

  • The head contains mitochondria (correct)
  • The midpiece is packed with organelles for energy
  • The tail aids in motility
  • The head contains genetic material
  • What happens to the zona pellucida after fertilization?

    <p>It becomes more impenetrable due to enzyme release</p> Signup and view all the answers

    What is the first stage of development that occurs after fertilization?

    <p>Cleavage divisions producing a two-cell stage</p> Signup and view all the answers

    What marks the beginning of human fertilization?

    <p>The union of an egg and sperm</p> Signup and view all the answers

    Which stage of oogenesis results in the release of a secondary oocyte?

    <p>Graafian follicle stage</p> Signup and view all the answers

    What occurs during sperm capacitation?

    <p>Sperm acquire the ability to penetrate the zona pellucida</p> Signup and view all the answers

    What is the purpose of the cortical reaction during fertilization?

    <p>To prevent additional sperm from entering the egg</p> Signup and view all the answers

    Which process occurs first after sperm binds to the zona pellucida?

    <p>Acrosome reaction</p> Signup and view all the answers

    What is the significance of sperm traversing through the female reproductive tract?

    <p>To reach the fallopian tubes where fertilization occurs</p> Signup and view all the answers

    Which structure helps sperm penetrate the zona pellucida?

    <p>Acrosome</p> Signup and view all the answers

    What is the result of the union of sperm and egg nuclei?

    <p>Formation of a zygote</p> Signup and view all the answers

    Signup and view all the answers

    Study Notes

    Human Fertilization: Stages and Changes

    • Fertilization Definition: The union of an ovum (egg) and sperm, creating a zygote. This initiates pregnancy.

    Stages of Fertilization

    • Preparation:
    • Oogenesis: Ovary develops immature eggs (oocytes) through stages (primordial, secondary, Graafian follicle) leading to ovulation.
    • Spermatogenesis: Testes produce sperm (spermatozoa) from spermatogonia during puberty.
    • Ovulation:
    • Ovulation Phase: Mature ovarian follicle (Graafian) bursts, releasing a secondary oocyte (ovum) into the peritoneal cavity, typically midway through the menstrual cycle.
    • Histological Changes: LH surge triggers follicle wall degeneration; granulosa cells reorganize to form the corpus luteum.
    • Sperm Journey:
    • Ejaculation and Capacitation: Sperm ejaculated into female tract, undergo capacitation (chemical changes) enhancing motility and zona pellucida penetration.
    • Travel: Sperm travel through cervix, uterus, and into fallopian tubes for fertilization.
    • Fertilization:
    • Zona Pellucida Penetration: Sperm binds to zona pellucida (glycoprotein layer), assisted by receptors and enzymes (e.g., acrosin).
    • Acrosome Reaction: Acrosome (sperm head cap) releases enzymes to digest zona pellucida, allowing sperm entry.
    • Fusion: Sperm and egg membranes fuse; sperm nucleus enters egg.
    • Block to Polyspermy:
    • Cortical Reaction: Cortical granules (in egg cytoplasm) release contents, changing zona pellucida structure preventing multiple sperm entry.
    • Zygote Formation:
    • Nuclei Union: Sperm and egg nuclei unite, forming a zygote with a diploid set of chromosomes.

    Histological Changes

    • Oocyte: Protected by zona pellucida and granulosa cells (support and barrier).
    • Sperm: Head (DNA), midpiece (mitochondria), tail (flagellum for motility).
    • Cortical Granules: In oocyte cytoplasm, crucial for cortical reaction, preventing polyspermy.
    • Zona Pellucida Transformation: Zona pellucida changes structure post-fertilization (due to enzymes).
    • Blastomere Formation: Zygote divides, initially producing two-cell and four-cell stages preserving zona pellucida until implantation.

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    Description

    Explore the intricate process of human fertilization, including the stages of oogenesis and spermatogenesis. This quiz covers the preparation, ovulation, and the sperm's journey to the ovum. Test your knowledge on the biological processes that initiate pregnancy.

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