Embryology Overview Quiz
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Questions and Answers

What is the approximate prevalence of ampulla implantation?

  • 11%
  • 0.5%
  • 12%
  • 70% (correct)

    • During which weeks does the process of organogenesis occur?

  • Week 6 to 12
  • Week 5 to 10
  • Week 3 to 8 (correct)
  • Week 1 to 4

    • Which method of organ formation involves the creation of an enclosed tube?

  • Condensation
  • Folds (correct)
  • Splits
  • Layering

    • On which day does the development of the heart begin?

    <p>Day 18 (D)</p> Signup and view all the answers

    What is the approximate weight of a fully developed placenta?

    <p>300-400 g (A)</p> Signup and view all the answers

    At what point in pregnancy does the placenta take over nourishment for the fetus?

    <p>Week 12 (B)</p> Signup and view all the answers

    What is the primary source of nourishment for the developing embryo before the placenta is formed?

    <p>Yolk sac (C)</p> Signup and view all the answers

    Which of the following hormones is NOT secreted by the placenta?

    <p>Oxytocin (C)</p> Signup and view all the answers

    What is the condition where the placenta is located over the internal cervical opening called?

    <p>Placenta previa (B)</p> Signup and view all the answers

    What major risk does placenta previa pose during the second half of pregnancy?

    <p>Vaginal bleeding (A)</p> Signup and view all the answers

    What is fetal alcohol syndrome primarily characterized by?

    <p>Abnormal brain growth and facial features (A)</p> Signup and view all the answers

    Which structure routes the embryo's blood into the chorionic villi?

    <p>Umbilical cord (C)</p> Signup and view all the answers

    How does the placenta contribute to passive immunity in the fetus?

    <p>By passing mother's antibodies (C)</p> Signup and view all the answers

    What is the duration of a typical human gestation period?

    <p>38-42 weeks (B)</p> Signup and view all the answers

    Which of the following processes occurs during the first week of prenatal development?

    <p>Fertilization (C)</p> Signup and view all the answers

    What is the lifespan of a sperm cell after ejaculation within the female reproductive tract?

    <p>24 to 48 hours (C)</p> Signup and view all the answers

    How long after ovulation is the oocyte viable for fertilization?

    <p>12 to 24 hours (A)</p> Signup and view all the answers

    What sequence of events is essential for fertilization to occur?

    <p>Intercourse must occur no more than 2 days before ovulation and no later than 24 hours after. (B)</p> Signup and view all the answers

    During which process do enzymes released from the acrosome digest the corona radiata and zona pellucida?

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

    Which term describes the process whereby the sperm's nucleus and centriole are released after fusion with the oocyte?

    <p>Membrane fusion (B)</p> Signup and view all the answers

    What happens to the sperm tail during its journey to the oocyte?

    <p>It helps propel the sperm via chemotaxis. (B)</p> Signup and view all the answers

    What is the main purpose of fertilization in embryological development?

    <p>To produce a unique set of genetic information (A)</p> Signup and view all the answers

    Which statement correctly describes the characteristics of the oocyte?

    <p>It has a large haploid nucleus and is non-motile (C)</p> Signup and view all the answers

    What component forms the extracellular matrix surrounding the oocyte?

    <p>Zona pellucida (B)</p> Signup and view all the answers

    What primarily defines the function of the placenta in embryological development?

    <p>Transporting nutrients and waste between the mother and fetus (B)</p> Signup and view all the answers

    Which option correctly depicts the production differences between sperm and oocyte?

    <p>Sperm are produced continuously from puberty while oocytes are produced before birth (C)</p> Signup and view all the answers

    What feature is NOT associated with spermatozoa?

    <p>Have a non-motile structure (D)</p> Signup and view all the answers

    What is the significance of the Zona Pellucida in fertilization?

    <p>Acts as a barrier for unwanted sperm entry (B)</p> Signup and view all the answers

    What sets the secondary oocyte apart in terms of meiosis?

    <p>It remains arrested in Meiosis II until fertilization (C)</p> Signup and view all the answers

    What is the primary purpose of capacitation in sperm cells?

    <p>To prepare sperm for fertilizing the egg (A)</p> Signup and view all the answers

    What event initiates the acrosome reaction in sperm?

    <p>Binding of sperm to the oocyte's membrane (A)</p> Signup and view all the answers

    What is the role of calcium ions (Ca2+) during the cortical reaction?

    <p>To open protein channels in the oocyte membrane (C)</p> Signup and view all the answers

    How does the fast block to polyspermy occur?

    <p>By altering the membrane potential of the oocyte (B)</p> Signup and view all the answers

    What triggers the release of hydrolytic enzymes from lysosomes during fertilization?

    <p>Influx of Ca2+ into the oocyte (D)</p> Signup and view all the answers

    What is the significance of ZP3 receptors during fertilization?

    <p>They facilitate sperm penetration into the ovum (B)</p> Signup and view all the answers

    What is the result of the acrosome reaction?

    <p>Release of enzymes that digest the zona pellucida (B)</p> Signup and view all the answers

    What causes the sperm membrane to become more fluid during capacitation?

    <p>Efflux of cholesterol from the sperm cell (D)</p> Signup and view all the answers

    What biochemical change in sperm during capacitation increases membrane fluidity?

    <p>Efflux of cholesterol (A)</p> Signup and view all the answers

    What triggers the acrosome reaction in sperm cells?

    <p>Binding to ZP3 receptors (D)</p> Signup and view all the answers

    What initiates the fast block to polyspermy?

    <p>Calcium influx to the oocyte (D)</p> Signup and view all the answers

    Which event occurs during the slow block to polyspermy?

    <p>Release of hydrolytic enzymes from lysosomes (C)</p> Signup and view all the answers

    What is the term for the single cell resulting from fertilization?

    <p>Zygote (D)</p> Signup and view all the answers

    What is the nuclear content of a zygote?

    <p>2n - diploid (D)</p> Signup and view all the answers

    What is the primary function of the trophoblast in the blastocyst?

    <p>Secreting human chorionic gonadotropin (A)</p> Signup and view all the answers

    During which stage does compaction of cells begin?

    <p>Morula stage (A)</p> Signup and view all the answers

    How does the blastocyst receive its nutrition before implantation?

    <p>From uterine secretions known as uterine milk (C)</p> Signup and view all the answers

    What marks the transition from a morula to a blastocyst?

    <p>Formation of the blastocyst cavity (A)</p> Signup and view all the answers

    What is the primary function of the bilaminar and trilaminar discs formed during gastrulation?

    <p>They serve as the building blocks for tissue and organ formation. (A)</p> Signup and view all the answers

    Which of the following terms describes the process of organ development occurring between weeks 3 to 8 of pregnancy?

    <p>Organogenesis (A)</p> Signup and view all the answers

    Which method of organ formation involves the creation of vesicles within cell layers?

    <p>Splits (C)</p> Signup and view all the answers

    On which day does the development of the eye and ear begin during embryonic development?

    <p>Day 22 (C)</p> Signup and view all the answers

    What is the approximate diameter of a fully developed placenta?

    <p>15-25 cm (B)</p> Signup and view all the answers

    What is the primary function of the umbilical vein during embryonic development?

    <p>Carries oxygenated blood from the placenta to the embryo (D)</p> Signup and view all the answers

    Which blood vessels are responsible for transporting deoxygenated blood from the embryo back to the placenta?

    <p>Umbilical arteries (D)</p> Signup and view all the answers

    What is the initial source of nourishment for the embryo before the establishment of the placenta?

    <p>Yolk sac (B)</p> Signup and view all the answers

    Which of the following processes is NOT a function of the placenta?

    <p>Releasing digestive enzymes (D)</p> Signup and view all the answers

    What structural layer of the gastrula eventually forms the body's muscles?

    <p>Mesoderm (A)</p> Signup and view all the answers

    What role does the yolk sac play before the placenta is formed?

    <p>It nourishes the developing embryo. (C)</p> Signup and view all the answers

    Which of the following is NOT a function of the placenta?

    <p>Oxygen production (D)</p> Signup and view all the answers

    What is the significance of chorionic villi in placental development?

    <p>They facilitate the exchange of nutrients and gases. (A)</p> Signup and view all the answers

    What condition is characterized by the presence of the placenta over the internal cervical opening?

    <p>Placenta previa (C)</p> Signup and view all the answers

    How does maternal blood interact with the fetal blood in the placenta?

    <p>They do not mix at all. (A)</p> Signup and view all the answers

    Which hormone is secreted by the placenta to maintain pregnancy and support fetal growth?

    <p>Human chorionic gonadotropin (hCG) (A)</p> Signup and view all the answers

    What is a primary characteristic of fetal alcohol syndrome?

    <p>Poor growth and abnormalities in facial characteristics (B)</p> Signup and view all the answers

    How is the umbilical cord related to the yolk sac?

    <p>It routes blood from the yolk sac to fetal organs. (A)</p> Signup and view all the answers

    What is the significance of chemotaxis in sperm movement towards the oocyte?

    <p>It guides sperm using chemical signals. (D)</p> Signup and view all the answers

    During which stage of prenatal development does organ formation primarily occur?

    <p>Gastrulation (D)</p> Signup and view all the answers

    How long is the oocyte viable for fertilization after ovulation?

    <p>12 to 24 hours (A)</p> Signup and view all the answers

    Which of the following accurately describes the acrosome reaction?

    <p>It involves the release of enzymes to penetrate the zona pellucida. (C)</p> Signup and view all the answers

    What environmental condition must be present for optimal sperm mobility?

    <p>Acidic environment (C)</p> Signup and view all the answers

    What event occurs shortly after the sperm membrane fuses with the oocyte?

    <p>Cortical reaction is triggered. (B)</p> Signup and view all the answers

    What is the process called whereby the initial single cell formed from fertilization undergoes division and differentiation?

    <p>Cleavage (C)</p> Signup and view all the answers

    What enzyme is responsible for breaking down hyaluronan in the corona radiata?

    <p>Hyaluronidase (A)</p> Signup and view all the answers

    What is the primary structural feature of the flagellum in sperm cells?

    <p>9 + 2 microtubule arrangement (D)</p> Signup and view all the answers

    Which component of seminal fluid primarily aids sperm motility and induces uterine contractions?

    <p>Prostaglandin (A)</p> Signup and view all the answers

    Why is fructose used as the energy source for sperm cells in seminal fluid instead of glucose?

    <p>Glucose promotes bacterial growth (C)</p> Signup and view all the answers

    What is the main function of the acrosome in sperm?

    <p>Digest the zona pellucida and corona radiata (D)</p> Signup and view all the answers

    Which part of the male reproductive system produces 60-70% of the seminal fluid?

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

    During which phase is embryological development classified before reaching fetal development?

    <p>Embryonic phase (C)</p> Signup and view all the answers

    Which structure in a sperm cell allows for motility?

    <p>Tail (flagellum) (D)</p> Signup and view all the answers

    What is the main role of capacitation in sperm cells?

    <p>It enhances sperm motility and membrane fluidity. (C)</p> Signup and view all the answers

    During the acrosome reaction, what triggers the release of acrosomal enzymes?

    <p>Binding to ZP3 receptors on the zona pellucida. (B)</p> Signup and view all the answers

    What physiological change occurs during the fast block to polyspermy?

    <p>Influx of Ca2+ that alters membrane potential. (D)</p> Signup and view all the answers

    What is the process that results in the gradual change of the zona pellucida due to sperm entry?

    <p>Slow block to polyspermy. (B)</p> Signup and view all the answers

    What is released by the trophoblast during early pregnancy?

    <p>Human chorionic gonadotropin (hCG). (A)</p> Signup and view all the answers

    What characterizes the inner cell mass of the blastocyst?

    <p>It becomes embryoblast. (B)</p> Signup and view all the answers

    Which of these events occurs during the first week of embryonic development?

    <p>Formation of the zygote and cleavage. (C)</p> Signup and view all the answers

    What happens to the zona pellucida after fertilization?

    <p>It is digested to aid embryo implantation. (D)</p> Signup and view all the answers

    Study Notes

    Embryology

    • Embryological development occurs from fertilization to the first eight weeks.
    • Fetal development occurs from week nine to birth.
    • Major systems are established during the embryonic period (weeks 3-8), which is also called organogenesis.
    • There are stages of development: fertilization, 1-week conceptus, 3-week embryo, 5-week embryo, 8-week embryo, 12-week fetus.
    • The lengths of each development stage are provided in millimeters (mm).
    • Gestation is 38-42 weeks (divided into three trimesters).

    Learning Objectives

    • Understanding the characteristics of gametes.
    • Description of fertilization.
    • Description of implantation.
    • Listing the main functions of the placenta.

    Gametes

    • Egg (Oocyte):
      • Largest cell (0.1 mm diameter)
      • Non-motile
      • Active metabolically
      • Produced in the ovary before birth
      • Limited numbers
      • Arrested in metaphase II of meiosis II until fertilized.
      • Release of 4 viable sperms during fertilization
    • Sperm:
      • Smallest cell (65 µm or 0.065 mm)
      • Highly motile
      • Little metabolic activity
      • Produced in the testes from puberty
      • Millions of sperm present
      • During maturation, there's a decrease in volume, followed by an increase with the gain of yolk granules.
      • Contains acrosome and nucleus
      • Contains mitochondria to produce ATP.
      • Contains flagellum with a 9+2 arrangement of microtubules to enable movement.

    Structural features of the secondary oocyte

    • Intracellular:
      • Large haploid nucleus
      • Dense cytoplasm
      • Surrounded by plasma membrane and vitelline membrane
    • Extracellular:
      • Oocytes surrounded by granulosa cells forming corona radiata.
      • Corona radiata originates from the Graafian follicle in the ovary.
      • Granulosa cells sit in a matrix containing hyaluronan (hyaluronic acid).
      • Zona pellucida—a clear, transparent zone—lies below the corona radiata.
      • The zona pellucida is an extracellular matrix from oocyte and granulosa cells.
      • It includes glycoproteins like ZP3 receptors.

    Structural features of spermatozoa

    • Head:
      • Contains the nucleus and acrosome, each within its own membrane.
      • Acrosome contains hydrolytic enzymes (acrosin and hyaluronidase).
      • Acrosin digests proteins in the zona pellucida, facilitating fertilization.
      • Hyaluronidase breaks down hyaluronan in the corona radiata.
    • Mid-piece:
      • Contains numerous mitochondria for ATP synthesis.
    • Flagellum:
      • Enables movement, formed from long tubulin proteins surrounding the axoneme (central microtubules with 9 doublets).
      • 9+2 arrangement characteristic of eukaryotic flagella.
      • Enables movement.

    Seminal Fluid

    • Seminal fluid is a transport medium for sperm.
    • A vital part of the fertilization procedure.
    • Contains 60-70% seminal fluid, produced by seminal vesicles,
    • Contains fructose (carbohydrate) for energy.
    • Prostaglandins induce uterine contractions.
    • Coagulase solidifies semen.
    • Prostate gland contributes roughly 30% to seminal fluid
    • Citrate is an energy source in the prostate gland fluid.

    Quiz 1 (Reproductive System)

    • Question 1: Male gametes are produced in the testes; female gametes in the ovaries.
    • Question 2: Corona radiata - a layer of cells surrounding the oocyte, supplying nutrients and facilitating development to the oocyte.
    • Question 3: Acrosome - a membrane-bound structure in the sperm containing hydrolytic enzymes to penetrate oocyte coverings for fertilization.
    • Question 4: 9+2 microtubules are arranged radially and 2 centrally to form the flagellum in sperm.
    • Question 5: Seminal vesicles and prostate gland produce seminal fluid that is vital as a transporting medium, and a source of nutrients and substances that assist in fertilization for the sperm, and also supplies energy for the sperm cells.
    • Question 6: Fructose is preferred to glucose because the latter is used by bacteria; therefore, fructose reduces competition.

    Implantation

    • Implantation, typically 6-8 days post-fertilization , involves the blastocyst burrowing into the uterine wall (endometrium).
    • The uterine wall envelops the blastocyst
    • Provides nourishment as a part of the embryo’s nourishment.
    • Human chorionic gonadotropin (hCG) is secreted for maintaining progesterone and to prevent menstruation.

    Early Placental Development

    • Trophoblast cells (outer cell mass) proliferate outside the blastocyst.
    • They penetrate the uterine cells and form finger-like projections called chorionic villi.
    • Cell membranes in multiple cells break down making regions of multinucleated cytoplasm and interact with maternal blood vessels.

    Ectopic Pregnancy

    • Ectopic pregnancy is an abnormal pregnancy that develops outside the uterine cavity.
    • Fallopian tube ectopic pregnancies are the most common site.
    • Prevalence is approximately 20 per 1000 pregnancies.
    • Early symptoms can mimic typical early pregnancy, often with abdominal pain.
    • Severity of complications correlates to the site of the ectopic pregnancy.

    Week 3: Gastrulation

    • Cells from the embryoblast (inner cell mass) proliferate, migrate, and form a trilaminar disc, which forms the ectoderm, mesoderm, and endoderm.
    • Gastrulation is a vital part of shaping tissues and organs.

    Week 3-8: Organogenesis

    • The organs of the embryo start developing during the embryonic period (weeks 3–8).
    • The organization process includes folding, splitting, and condensation.

    Organogenesis

    • Major organ systems begin to form during weeks 3–8.
    • Key time-points include:
      • CNS and spinal cord (day 15)
      • Heart (day 18)
      • Eye and ear (day 22)
      • Digestive system (day 28)
      • Respiratory tract (day 35)
      • Skeletal system (day 35)
      • Muscular system (day 38)

    Umbilical Cord Structure

    • The umbilical cord contains embryonic blood vessels and carries blood to and from the placenta.
    • One umbilical vein carries oxygenated blood to the embryo.
    • Two umbilical arteries carry deoxygenated blood back to the placenta.

    Early Cardiovascular System

    • One umbilical vein carries oxygenated blood from the placenta to the embryo and into the embryonic circulation and through the inferior vena cava.
    • Two umbilical arteries carry deoxygenated blood from the embryo back to the placenta.

    Quiz 4

    • Question 1: The mesoderm layer forms the muscles of the body.
    • Question 2: hCG maintains the corpus luteum, which secretes progesterone to maintain the uterine lining in early pregnancy and prevents menstruation.
    • Question 3: Trophoblast cells penetrate the endometrium and create chorionic villi.
    • Question 4: The main processes for organ formation from the trilaminar disc are folding, splitting, and condensation.
    • Question 5: The yolk sac provides nourishment before the placenta fully develops.
    • Question 6: Placental functions include gas exchange, excretion, passive immunity, and anchorage.

    Placenta Previa

    • A placental abruption where the placenta forms over or near the internal os of the cervix, causes vaginal bleeding in second-half pregnancy.
    • Requires close monitoring.
    • Early delivery (C-section) may be necessary.

    Foetal Alcohol Syndrome (FAS)

    • Maternal alcohol use during pregnancy causes fetal abnormalities (FAS), with decreased growth, brain malformations, and specific facial features.
    • This condition is considered the most serious fetal alcohol spectrum disorder.

    Quiz 3 (Pregnancy)

    • Question 1: Cleavage is the stage characterized by rapid mitotic cell division.
    • Question 2: Oviduct.
    • Question 3: Uterine secretions (uterine milk) nourish the embryo.
    • Question 4: The cells' movement is facilitated by cilia and fimbriae, which waft them toward the uterus for implantation.
    • Question 5: Blastulation transforms the ball of cells into a blastocyst.
    • Question 6: Outer cell mass – trophoblast; inner cell mass – embryoblast.

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    Description

    Test your knowledge on embryological development from fertilization to birth. This quiz covers the stages of development, characteristics of gametes, and important functions of the placenta. Perfect for students studying human biology and embryology.

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