Oogenesis Quiz
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Questions and Answers

What is the outcome of the maturation process of oogonia after they differentiate into primary oocytes?

  • They undergo mitosis to produce more oogonia.
  • They enter meiosis and arrest during prophase I. (correct)
  • They transition directly into mature ova.
  • They all survive and develop into primordial follicles.
  • At what stage do primary oocytes become surrounded by a layer of flat epithelial cells?

  • After the degeneration of all other oogonia.
  • During their mitotic division.
  • Immediately following fertilization.
  • When they begin developing into primordial follicles. (correct)
  • Which event marks the beginning of cell death in oogonia and primary oocytes?

  • The differentiation of oogonia begins.
  • The total germ cell count reaches its maximum. (correct)
  • Primary oocytes complete their first meiotic division.
  • The primary oocytes are formed from oogonia.
  • What characterizes the diplotene stage that primary oocytes enter before birth?

    <p>A lacy network of chromatin formation.</p> Signup and view all the answers

    What primarily happens to the majority of oogonia by the seventh month of development?

    <p>They degenerate and become atretic.</p> Signup and view all the answers

    What initiates the development of primordial follicles?

    <p>The arrest of primary oocytes in prophase I.</p> Signup and view all the answers

    What is the maximum number of germ cells reached during the development of oocytes?

    <p>7 million.</p> Signup and view all the answers

    Why do primary oocytes not complete their first meiotic division before puberty?

    <p>They are arrested in prophase I and enter a resting stage.</p> Signup and view all the answers

    What is the role of oocyte maturation inhibitor (OMI)?

    <p>To prevent premature ovulation</p> Signup and view all the answers

    Which layer develops as granulosa cells proliferate and form a stratified epithelium?

    <p>Primary follicle</p> Signup and view all the answers

    How many primary oocytes are typically present at the onset of puberty?

    <p>40,000</p> Signup and view all the answers

    What is the longest stage in the maturation of follicles?

    <p>Antral stage</p> Signup and view all the answers

    What results from the coalescence of fluid-filled spaces between granulosa cells?

    <p>Appearance of antrum</p> Signup and view all the answers

    What cellular change occurs in surrounding follicular cells as primordial follicles begin to grow?

    <p>They change from flat to cuboidal</p> Signup and view all the answers

    What is the purpose of the finger-like processes extending from follicular cells?

    <p>To transport materials to the oocyte</p> Signup and view all the answers

    During which phase does the follicle become known as a mature vesicular follicle or Graafian follicle?

    <p>Preovulatory phase</p> Signup and view all the answers

    What structure forms from the granulosa cells surrounding the oocyte at maturity?

    <p>Cumulus oophorus</p> Signup and view all the answers

    What triggers the preovulatory growth phase in the secondary follicle?

    <p>Surge in luteinizing hormone (LH)</p> Signup and view all the answers

    What happens to the first polar body after meiosis I is completed?

    <p>It may undergo a second division.</p> Signup and view all the answers

    Which of the following statements about meiosis II is correct?

    <p>It only completes if the oocyte is fertilized.</p> Signup and view all the answers

    What is the ploidy of the secondary oocyte?

    <p>1N</p> Signup and view all the answers

    Which of the following structures merges with the ovarian connective tissue?

    <p>Theca externa</p> Signup and view all the answers

    What occurs to most follicles during the ovarian cycle?

    <p>They degenerate and become atretic.</p> Signup and view all the answers

    What is the main function of the theca interna cells?

    <p>Steroid hormone secretion.</p> Signup and view all the answers

    Study Notes

    Oogenesis Overview

    • Oogenesis is the process where oogonia develop into mature oocytes.
    • Begins with primordial germ cells (PGCs) differentiating into oogonia in the female gonad.

    Development Stages

    • At 3 months of gestation, oogonia are in clusters, surrounded by flat epithelial follicular cells.
    • Majority of oogonia continue mitosis; some enter meiosis and form primary oocytes.
    • Maximum germ cell count reaches about 7 million by the 5th month.
    • Cell death leads to degeneration, with most oogonia and primary oocytes becoming atretic by 7 months gestation.

    Primary Oocyte Characteristics

    • Surviving primary oocytes arrest in prophase of meiosis I, forming primordial follicles.
    • The arrested state is maintained by oocyte maturation inhibitor (OMI) produced by follicular cells.
    • Total primary oocytes at birth estimated between 600,000 to 800,000, reducing to approximately 40,000 by puberty.

    Maturation at Puberty

    • At puberty, 15 to 20 primordial follicles begin maturing monthly.
    • Follicular cells transition from flat to cuboidal, forming primary follicles with stratified granulosa cells.
    • Granulosa cells create the zona pellucida around oocytes; theca folliculi develops into internal and external layers.

    Follicle Development Stages

    • Maturation progresses through three stages:
      • Primary or preantral
      • Secondary or antral (vesicular)
      • Preovulatory (Graafian follicle)
    • The antral stage accumulates fluid, with mature vesicular follicles reaching 25 mm or more in diameter before ovulation.

    Luteinizing Hormone Surge

    • A surge in luteinizing hormone (LH) initiates the preovulatory growth phase.
    • Meiosis I completes, creating unequal daughter cells; one becomes the secondary oocyte while the other is the first polar body.

    Secondary Oocyte Arrest

    • The secondary oocyte enters meiosis II but is arrested in metaphase approximately 3 hours before ovulation.
    • Completion of meiosis II occurs only if fertilization takes place, with degeneration of the oocyte if not fertilized within 24 hours post-ovulation.

    Fertilization Process

    • Secondary oocyte is released surrounded by follicle cells (nurse cells).
    • Sperm enzymes, released from the acrosome, penetrate the zona pellucida to reach the egg cytoplasm for fertilization.

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    Related Documents

    Oogenesis PDF

    Description

    Test your knowledge on the process of oogenesis, including primary oocyte development and meiosis stages. This quiz covers key concepts and terminology necessary for understanding female gametogenesis.

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