Animal Reproductive Biology Quiz
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Questions and Answers

What is the typical copulation duration for a stallion?

  • 15-30 seconds (correct)
  • 1-2 minutes
  • 45-60 seconds
  • 5-10 seconds

    • Which breeding method is recommended for heifers that have reached full growth?

  • Natural breeding (correct)
  • Artificial insemination
  • Embryo transfer
  • Synchronised ovulation

    • What common risk is associated with copulation in younger heifers?

  • Excessive bleeding in the vagina
  • Injury to the ovaries
  • Trauma to the uterus (correct)
  • Infection in the cervix

    • During which phase does meiosis I begin in ovogenesis?

    <p>Fetal development</p> Signup and view all the answers

    What is metrorrhagia in the context of coitus?

    <p>Bleeding after copulation</p> Signup and view all the answers

    What occurs to the secondary oocyte if fertilization takes place?

    <p>It completes meiosis 2, forming an ovum and a second polar body.</p> Signup and view all the answers

    What is the role of the zona pellucida surrounding the oocyte?

    <p>To act as a barrier to prevent sperm from penetrating.</p> Signup and view all the answers

    What is the primary role of Growth Differentiation Factor 9 (GDF9) in folliculogenesis?

    <p>To act on granulosa cells for local follicle development.</p> Signup and view all the answers

    Which structure is the final product after the ovulation of a mature Graafian follicle?

    <p>Secondary oocyte and first polar body.</p> Signup and view all the answers

    What effect does increasing estrogen levels have during estrus?

    <p>It stimulates the release of luteinizing hormone (LH).</p> Signup and view all the answers

    Study Notes

    Coitus

    • Coitus involves the insertion of the erect penis into the vagina, followed by ejaculation.
    • The location of semen deposition varies depending on the animal: cattle, buffalo, mare, sow, and ram each have distinct areas.
    • The ram's urethral process forces semen distribution, ensuring its effectiveness despite low volume.

    Duration of Coitus

    • Cattle and sheep have brief copulation lasting only a few seconds.
    • Stallion copulation lasts 15-30 seconds.
    • Dogs have a copulatory tie that can last 15-30 minutes.
    • Swine exhibit a copulatory tie for an average of 3-8 minutes.
    • Failure to ejaculate is common in swine.

    Dangers of Coitus

    • Young heifers can experience uterine injuries with overly large bulls.
    • Lacerations and trauma can lead to post-coital swelling, bleeding, and straining.
    • Artificial insemination is preferred for heifers' growth, while natural breeding is recommended for mature heifers.
    • The first insemination should be natural to allow for size compatibility between the bull and heifer.
    • Foreign breed pairings can lead to dystocia and oversized embryos.
    • Artificial insemination is advised for situations where natural breeding poses risks.

    Metrorrhagia

    • Metrorrhagia is bleeding after coitus.
    • While sometimes normal, it can indicate underlying issues.

    Ovulation

    • The maturation of an oocyte is known as ovogenesis.
    • Meiosis I begins during fetal development, while meiosis I is completed after puberty, producing a secondary oocyte and the first polar body.
    • The secondary oocyte then begins meiosis II.
    • If fertilization occurs, meiosis II is completed, resulting in an ovum and a second polar body.
    • Without fertilization, meiosis II doesn't complete.

    Folliculogenesis

    • The process starts with a primordial follicle and progresses through stages: primary, secondary, mature Graafian follicle, corpus luteum, and corpus albicans.
    • The mature Graafian follicle houses the secondary oocyte and the first polar body.

    Cumulus Oocyte Complex

    • The cumulus oocyte complex comprises the oocyte, follicular fluid, zona pellucida, and corona radiata cells.
    • These cells play a vital nutritive and protective role.

    Zona Pellucida (ZP)

    • The zona pellucida is a tough, acellular glycoprotein layer surrounding the oocyte and produced by the oocyte itself.
    • It acts as a barrier to sperm penetration and has species-specific receptors to prevent fertilization by sperm of other species.

    Corona Radiata

    • The corona radiata is the outermost layer of cells around the oocyte.
    • It's composed of cumulus oophorus cells.

    Regulation of Follicular Growth

    • Growth differentiation factor 9 (GDF9) is a protein produced by the theca cells, acting as a paracrine factor to stimulate granulosa cells.
    • Growth differentiation factor 9B (GDF9B) is produced by both granulosa and theca cells, acting as an autocrine inhibitor for follicular growth.
    • Activin is a hormone produced by granulosa cells, acting as a paracrine factor to enhance the growth and maturation of the dominant follicle.

    Mechanism of Ovulation

    • Estrogen levels rise during estrus, triggering LH release.
    • The pre-ovulatory LH surge causes the expansion of the cumulus cell layer, separating the oocyte from the follicular wall.
    • This surge also increases blood supply to the ovary and follicle, leading to vascular permeability.
    • Plasminogen and prostaglandins enter the follicle through the increased permeability.
    • Plasminogen activation converts plasminogen into plasmin, which degrades collagen and weakens the follicular wall.
    • Prostaglandin E and F synthesis and release further contribute to muscle contraction and expulsion of the oocyte.

    Fimbria

    • Fimbria are finger-like projections on the fallopian tube's infundibulum.
    • They move and contract for guiding the oocyte into the fallopian tube.
    • Estrogen increases their activity.

    Time of Ovulation

    • Various animal species have different ovulation timings: cows (10-12 hours after estrus), mares (2 days before the end of heat), ewes (6-12 days before the end of heat), goats (4-6 hours before the end of heat), sows (24-48 hours after estrus), cats (induced 24 hours after coitus), and camels (induced 24-36 hours after coitus).

    Fertilization

    • Fertilization involves the union of a mature sperm and ovum to form a zygote.

    Factors Facilitating Fertilization

    • Sperm maturation in the epididymis, sperm capacitation, and the acrosomal reaction are essential.
    • Sperm transport to the egg is a complex process influenced by fallopian tube length, location, and sperm motility.
    • Ovum transport relies on fimbriae, follicular fluid, cilia, and muscle contractions.

    Mechanisms of Sperm Transport

    • Fertilization occurs at the ampullary-isthmic junction.
    • Ejaculation in the dorsal fornix of the vagina, estual mucus for sperm movement through the cervix, and selection of sperm in the uterus are crucial steps.
    • Oxytocin and prostaglandin in semen contribute to contractions for sperm transport.
    • Sperm await the ovum at the ampullary-isthmic junction.
    • Abnormal sperm are either phagocytized or lost via the cervix.

    Cervical Mucus

    • It protects, nourishes, and has antimicrobial properties.

    Sperm Attachment to Fallopian Tube

    • Temporary attachment to the fallopian tube epithelium for protection and capacitation.

    Barriers to Sperm

    • The cervix is a challenging barrier, due to mucus and the annular ring.
    • The cortical reaction hardens the zona pellucida, preventing further sperm entry.

    Syngamy

    • Fusion of male and female pronuclei to form a zygote.

    Abnormal Fertilization

    • Polyspermy (multiple sperm penetration) leads to a triploid zygote, typically ending in death.
    • Polygyny (maturation of the egg without the second polar body expulsion) also results in a triploid zygote.
    • Gynogenesis (non-development of the male pronucleus) leads to a haploid embryo that dies.
    • Androgenesis (non-development of the female pronucleus) results in a haploid embryo that doesn't develop.
    • Ovum wandering can occur internally or externally, and is common in bitches.
    • Superfecundation involves impregnation by two different males.
    • Superfetation is the gestation of fetuses from separate ovulations, a rarer phenomenon.

    Twins

    • Identical twins (monozygotic) form when a single zygote splits into two, sharing the same sex and DNA.
    • Fraternal twins (dizygotic) result from fertilization of two eggs by two sperm, sharing half of their DNA like regular siblings.
    • Twin incidence rises with maternal age.

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    Description

    This quiz covers the mechanics and duration of coitus in various animals, along with potential dangers associated with natural breeding. Learn about species-specific copulation times, injury risks, and the role of artificial insemination in reproductive health.

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