Sex Determination and Development
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Questions and Answers

What is the primary role of pulsatile GnRH secretion?

  • To regulate testosterone levels
  • To control the secretion of FSH and LH (correct)
  • To initiate oocyte maturation
  • To directly stimulate sperm production

    • Which hormone inhibits FSH secretion?

  • Gonadotropin
  • Testosterone
  • Activin
  • Inhibin (correct)

    • What is the role of Leydig cells in the male reproductive system?

  • They produce testosterone (correct)
  • They store sperm
  • They produce inhibin
  • They conduct sperm

    • What triggers spermatogenesis?

    <p>Both gonadotropins and testosterone</p> Signup and view all the answers

    Which of the following is NOT a function of Sertoli cells?

    <p>Producing testosterone</p> Signup and view all the answers

    What is an effect of androgens on male development?

    <p>Development of secondary sex characteristics</p> Signup and view all the answers

    Which male accessory gland is responsible for secreting a fluid that nourishes sperm?

    <p>Seminal vesicles</p> Signup and view all the answers

    Which environmental factor does NOT influence reproductive physiology in women?

    <p>Caffeine consumption</p> Signup and view all the answers

    What substance must spermatids develop into to participate in fertilization?

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

    After puberty, how frequently does tonic GnRH release occur?

    <p>Every 1-3 hours</p> Signup and view all the answers

    What is the primary reason male gametogenesis has a continuous production of sperm from puberty until death?

    <p>Mitosis resumes at puberty, supported by a resting pool of spermatogonia</p> Signup and view all the answers

    What occurs to primary oocytes before puberty in female gametogenesis?

    <p>They arrest development after the first stage of meiosis</p> Signup and view all the answers

    Which of the following describes the fate of the secondary oocyte after ovulation?

    <p>It completes the second meiotic division only if fertilized</p> Signup and view all the answers

    What is the main function of the hormone aromatase in the reproductive system?

    <p>To convert androgens to estrogens</p> Signup and view all the answers

    At birth, what is unique about female gametogenesis compared to male gametogenesis?

    <p>All eggs are already produced</p> Signup and view all the answers

    Which of the following best describes the feedback mechanisms of reproductive hormones in both sexes?

    <p>Positive feedback dominates in females during ovulation</p> Signup and view all the answers

    What role does inhibin play in the regulation of reproductive hormones?

    <p>Inhibits the secretion of FSH</p> Signup and view all the answers

    What happens during the first meiotic division in female gametogenesis?

    <p>One secondary oocyte and a first polar body are formed</p> Signup and view all the answers

    In male gametogenesis, what is the outcome of the first meiotic division?

    <p>Two identical spermatocytes are produced</p> Signup and view all the answers

    What is the primary hormonal trigger for both male and female gametogenesis?

    <p>LH release</p> Signup and view all the answers

    What is the primary role of anti-Müllerian hormone (AMH) during the early follicular phase?

    <p>Inhibits the development of other follicles in the current cycle</p> Signup and view all the answers

    During which phase of the ovarian cycle does ovulation occur?

    <p>Mid-late follicular phase</p> Signup and view all the answers

    Which hormones are primarily secreted by the luteal cells of the corpus luteum?

    <p>Estrogen and progesterone</p> Signup and view all the answers

    What occurs in the late luteal phase if pregnancy does not happen?

    <p>The corpus luteum degenerates into corpus albicans</p> Signup and view all the answers

    What is the significance of the surge in LH and FSH during the mid-late follicular phase?

    <p>They stimulate the final maturation of the dominant follicle</p> Signup and view all the answers

    What is a primary characteristic of secondary follicles during follicular development?

    <p>Massive multiplication of granulosa cells begins</p> Signup and view all the answers

    What initiates the proliferative phase of the uterine cycle?

    <p>Elevated estrogen levels from the growing follicles</p> Signup and view all the answers

    Which structure forms from the ruptured follicle after ovulation?

    <p>Corpus luteum</p> Signup and view all the answers

    What causes the endometrium to thicken during the menstrual cycle?

    <p>Growing levels of estrogen from secondary follicles</p> Signup and view all the answers

    What happens to primary oocytes if they are not selected for maturation during follicular development?

    <p>They undergo atresia</p> Signup and view all the answers

    What is the function of the SRY gene in sex determination?

    <p>It encodes a protein that initiates male reproductive development.</p> Signup and view all the answers

    What is the significance of the presence of testosterone during male embryonic development?

    <p>It leads to the formation of the epididymis, vas deferens, and seminal vesicle.</p> Signup and view all the answers

    Which structure develops in the absence of both testosterone and Anti-Mullerian hormone (AMH)?

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

    What happens to the Müllerian duct in male embryonic development?

    <p>It regresses due to AMH produced by Sertoli cells.</p> Signup and view all the answers

    How many pairs of sex chromosomes are present in a typical diploid human cell?

    <p>1 pair of sex chromosomes</p> Signup and view all the answers

    Which hormone is responsible for the regression of the gonadal medulla in female embryonic development?

    <p>None, it regresses naturally</p> Signup and view all the answers

    What type of cells produce testosterone in the developing male fetus?

    <p>Leydig cells</p> Signup and view all the answers

    The diploid number of chromosomes in humans is represented as which of the following?

    <p>2n</p> Signup and view all the answers

    What role do gametes play in the context of human reproduction?

    <p>They are haploid cells that combine to form a diploid zygote.</p> Signup and view all the answers

    What is the outcome if the SRY gene is absent in an embryo?

    <p>The embryo develops into a female.</p> Signup and view all the answers

    Study Notes

    Sex Determination

    • Sperm determines sex by carrying either an X or Y chromosome
    • One pair of sex chromosomes (XX or XY) determines gender
    • The Y chromosome is essential for male development

    Sex Chromosome Development

    • Autosomal cells are somatic cells, having 22 pairs of non-sex chromosomes
    • Gametes (egg and sperm cells) are haploid, meaning they contain 23 chromosomes.
    • Diploid cells have two sets of chromosomes, one from each parent, resulting in a total of 46 chromosomes.
    • Autosomal cells exclude sex cells/gametes

    Bipotential Reproductive Structures

    • Early embryos have bipotential reproductive structures that have the potential to become male or female structures.
    • Chemicals/hormones determine the structure's development to either male or female structures
    • The gene SRY, found on the Y chromosome, is crucial
      • Leads to the production of the testes-determining factor when the SRY gene is present.
      • Results in testes formation otherwise, female structures develop

    Sexual Differentiation

    • Male Development (Testosterone & AMH Present):
      • Gonadal cortex regresses (shrinks and disappears)
      • Gonadal medulla develops into testes
      • Wolffian duct forms epididymis, vas deferens, and seminal vesicle; testosterone converts the Wolffian duct into male accessory structures
      • Leydig / interstitial cells secrete testosterone
    • Female Development (Testosterone & AMH Absent):
    • Gonadal cortex develops into ovaries
    • Gonadal medulla regresses
    • Wolffian duct regresses
    • Mullerian duct develops into fallopian tubes, uterus, cervix, and upper half of the vagina.

    Gametogenesis

    • Male Gametogenesis:

      • Begins in the fetus but doesn't proceed past mitosis until puberty.
      • Germ cells are spermatogonia and do not divide until puberty.
      • Mitosis resumes during puberty
      • Continuous sperm production begins during puberty and continues until death.

    • Female Gametogenesis:

      • Oogonia complete mitotic stages before birth
      • Female meiosis begins before birth, and oocytes remain arrested in the primary oocyte phase until puberty.
      • Beginning meiosis 1 steps before birth.
      • Oocytes complete meiosis, eventually become eggs in the mature stage only if fertilized, one egg is produced per cycle.
      • Oocyte maturation only occurs when selected and triggered every month during puberty and continues until menopause.

    Basic Patterns of Reproduction

    • Both sexes produce androgens and estrogens.
    • Androgens are dominant in males
      • Testosterone is produced in the testes.
    • Estrogens are dominant in females
      • Estrogens, Progestins, and androgens are produced in the ovaries
    • Aromatase converts androgens to estrogens.
    • Positive and negative feedback pathways control reproductive function. GnRH, FSH and LH (pituitary gonadotropins) are released by different areas in the brain to control gamete production.

    Hormonal Control of Spermatogenesis

    • Feedback pathways govern spermatogenesis, with testosterone playing a crucial role.

    Primary and Secondary Sex Characteristics

    • Androgens influence primary and secondary sex characteristics in males.
    • Primary characteristics refer to reproductive ducts and organs.
    • Secondary characteristics include traits like pubic/axillary hair and muscular development.

    Female Reproduction

    • Organization of ovary tissues, development of follicles from primordial to mature to release egg to fertilization, and development of the corpus luteum for the next cycle.
    • The menstrual cycle has ovarian and uterine cycles that occur simultaneously but in different locations.
    • Follicle development begins with the primordial follicle and progresses to the formation of a mature follicle that releases an egg during ovulation.

    Menstrual Cycle

    • Ovarian and uterine cycles are synchronized, with alternating phases of follicular and luteal development in the ovaries, and accompanying proliferative and secretory phases in the uterus.

    Contraceptives

    • Various methods exist, including abstinence, sterilization, barrier methods, hormonal treatments, and intrauterine devices (IUDs).
    • Abstinence and sterilization are very effective, followed by barrier methods, intrauterine devices and lastly hormonal treatments ineffectiveness varies greatly.

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    Reproduction and Development (Physio 26 Gecko) PDF

    Description

    Explore the fascinating mechanisms of sex determination through chromosomes and hormonal influences. This quiz covers key concepts such as sex chromosomes, gametes, and bipotential reproductive structures essential for understanding gender development. Test your knowledge on the fundamental genetic factors involved in sexual differentiation.

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