Teratology and Embryology Overview
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What is the primary focus of teratology within embryology?

  • Examining malformations that occur during embryonic development (correct)
  • Analyzing postnatal development of infants
  • Investigating environmental factors leading to birth defects
  • Studying the genetic factors of embryonic development

    • Which historical view of malformations was prevalent in pre-medieval times?

  • Monsters were thought to be products of environmental factors.
  • Birth defects were considered a positive sign of happiness. (correct)
  • Congenital defects were associated with divine punishment.
  • Malformations were seen as evidence of genetic mutations.

    • What is the term used to describe the phenomenon of light marks of peculiar development in embryology?

  • Stigma (correct)
  • Malformation
  • Teratogen
  • Mutation

    • Which drug is associated with causing malformations of the ears?

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

    Which of the following congenital malformations is linked to maternal diabetes?

    <p>Congenital heart defects</p> Signup and view all the answers

    What growth condition can result from maternal alcoholism during pregnancy?

    <p>Fetal alcohol syndrome</p> Signup and view all the answers

    Which environmental factor can lead to fetal stress that may cause malformations?

    <p>Exposure to loud noises</p> Signup and view all the answers

    What is indicated by the incidence range of 2.0-5.6% of all births?

    <p>The occurrence of birth defects at birth</p> Signup and view all the answers

    At what stage is the conceptus referred to as a morula after fertilization?

    <p>16-32 blastomeres</p> Signup and view all the answers

    What structure develops from the trophoblasts around the dark cells in the morula stage?

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

    What is the primary purpose of the syncytiotrophoblast layer during implantation?

    <p>To digest endometrial tissue for nutrient absorption</p> Signup and view all the answers

    What role do sodium/potassium ATPases play in the formation of the blastocyst?

    <p>They initiate the influx of Na+ and subsequently water into the blastocyst</p> Signup and view all the answers

    What is the significance of the three different decidua during pregnancy?

    <p>They serve as sites for attachment and protection of the conceptus</p> Signup and view all the answers

    When does the zona pellucida typically rupture during embryo development?

    <p>On the fifth day after fertilization</p> Signup and view all the answers

    Where should implantation ideally occur in the uterus?

    <p>On the anterior or posterior wall</p> Signup and view all the answers

    What is the decidua basalis associated with during pregnancy?

    <p>The placenta site</p> Signup and view all the answers

    What differentiates the timing of meiosis initiation between oogenesis and spermatogenesis?

    <p>Oogenesis initiates once in a finite population, while spermatogenesis is continuous.</p> Signup and view all the answers

    How do gamete differentiation processes differ in oogenesis and spermatogenesis?

    <p>Spermatogenesis occurs while the cells are haploid; oogenesis occurs while diploid.</p> Signup and view all the answers

    Which of the following statements about the outcome of meiotic divisions in oogenesis and spermatogenesis is correct?

    <p>Oogenesis results in one functional gamete and polar bodies, while spermatogenesis results in four gametes.</p> Signup and view all the answers

    What is true about the cell cycle and meiosis completion in oogenesis and spermatogenesis?

    <p>Oogenesis has periods of arrest during the meiotic process, while spermatogenesis does not.</p> Signup and view all the answers

    Which temperature is optimal for the processes of oogenesis and spermatogenesis?

    <p>Spermatogenesis occurs at a lower temperature, specifically 33.6 degrees, while oogenesis occurs at 36.6 degrees.</p> Signup and view all the answers

    In what manner do the chromosomes behave during the meiotic prophase in oogenesis compared to spermatogenesis?

    <p>All chromosomes in oogenesis undergo equivalent transcription and recombination.</p> Signup and view all the answers

    Which of the following statements about the initiation and development of oocytes and spermatozoa is true?

    <p>Oogenesis initiates before birth, and all ova are present at that time.</p> Signup and view all the answers

    What is the role of Sertoli cells in the process of spermiohistogenesis?

    <p>Sertoli cells support the spermatids by maintaining attachment during the phases of spermiogenesis.</p> Signup and view all the answers

    At which embryonic month does the neurocranium begin its development?

    <p>2nd month</p> Signup and view all the answers

    Which of the following bones is NOT formed by endochondral ossification?

    <p>Os parietale</p> Signup and view all the answers

    What is the fate of the anterior fontanelle?

    <p>Closes at 1.5 years</p> Signup and view all the answers

    Which of the following bones is specifically formed through intermembranous ossification in the viscerocranium?

    <p>Os zygomaticus</p> Signup and view all the answers

    What is the typical characteristic of the ossification process of the limb bones?

    <p>It is initiated under the influence of BMP</p> Signup and view all the answers

    At what age does the posterior fontanelle typically ossify?

    <p>At 1 year</p> Signup and view all the answers

    Which ossification type is characteristic for ossicles such as malleus, incus, and stapes?

    <p>Chondral ossification</p> Signup and view all the answers

    Which bones are formed by desmogenic processes?

    <p>Os parietale and os frontale</p> Signup and view all the answers

    What is the role of prostaglandin E2 and prostaglandin I2 in the fetal circulation?

    <p>They maintain the potency of ductus venosus and ductus arteriosus.</p> Signup and view all the answers

    At what embryonic week does the lymphatic system begin to develop?

    <p>5th week</p> Signup and view all the answers

    Which of the following structures does not change in postnatal life?

    <p>Cisternae chyli</p> Signup and view all the answers

    What is the outcome of improper septation during heart development?

    <p>Truncus arteriosus persistence</p> Signup and view all the answers

    Which factor is NOT typically associated with heart development?

    <p>Overproduction of erythropoietin</p> Signup and view all the answers

    Which congenital anomaly involves the presence of an open ventricular septum?

    <p>Foramina interventricularis</p> Signup and view all the answers

    Which stage of heart development includes the folding of the embryo?

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

    What does the umbilical vein become after birth?

    <p>Ligamentum teres uteri</p> Signup and view all the answers

    Study Notes

    Teratology and Embryology

    • Teratology is the study of birth defects.
    • Ontogenesis refers to the development of an organism from fertilization to adulthood.
    • Experimental embryology involves manipulating embryos to study development.
    • Stigma in embryology indicates slight developmental abnormalities, often considered signs of unique features.
    • Teratogens are substances that can induce congenital malformations.

    Causes of Congenital Malformations

    • Genetic factors: mutagenic responses to radiation, chemicals, and chromosomal abnormalities.
    • Environmental factors:
      • Drugs: thalidomide (ear malformations), warfarin (nose hypoplasia), tetracycline (enamel dysplasia)
      • Maternal conditions: diabetes (heart defects), alcoholism (fetal alcohol syndrome)
      • Intrauterine infections: toxoplasmosis, CMV, rubella (oligohydramnios)
      • Physical factors: noise, vibration, radiation
      • Hypoxia: fetal stress leading to malformations

    Gametogenesis

    • Oogenesis: female gamete formation.
      • Meiosis initiated once in a finite population of cells.
      • One gamete produced per meiosis.
      • Completion of meiosis delayed for months or years.
      • Differentiation occurs while diploid.
      • All chromosomes exhibit equivalent transcription and recombination.
      • Oogenesis occurs at normal body temperature.
      • Unequal divisions, oocytes only mature after fertilization.
      • Begins before birth.
      • All ova are present at birth.
      • Oocytes are immotile.
    • Spermatogenesis: male gamete formation.
      • Meiosis initiated continuously in a mitotically dividing stem cell population.
      • Four gametes produced per meiosis.
      • Meiosis completed in days or weeks.
      • Differentiation occurs while haploid.
      • Sex chromosomes excluded from recombination and transcription.
      • Spermatogenesis occurs at 33.6 degrees Celsius.
      • Equal divisions, spermatozoa are mature cells.
      • Begins at puberty.
      • Spermatozoa develop at puberty and onwards.
      • Spermatozoa are motile.

    Spermiohistogenesis

    • Spermiogenesis occurs while cells are attached to Sertoli cells via gap junctions.
    • Four phases: Golgi phase, cap phase, acrosome phase, maturation phase.
    • Golgi phase: spermatids develop polarity and the Golgi apparatus forms enzymes that will become the acrosome.

    Morula and Blastocyst

    • Morula: a solid ball of 16-32 blastomeres formed at day 4 after fertilization.
    • Trophoblast: outer cells of the morula that will develop into the placenta and membranes.
    • Embryoblast: inner cells of the morula that will become the embryo.
    • Blastocyst: formed as fluid enters the morula, creating a blastocoel (fluid-filled cavity).
    • Embryonic pole: where the embryoblast is located.
    • Aembryonic pole: the opposite side of the blastocyst.

    Implantation

    • Implantation typically occurs in the anterior or posterior wall of the uterus.
    • Syncytiotrophoblast: a layer that develops from the trophoblast and secretes enzymes to penetrate the endometrium.
    • Decidua: the functional layer of the endometrium during pregnancy.
      • Decidua capsularis: closest to the uterine cavity.
      • Decidua basalis: at the placental site.

    Cranial Ossification

    • Neurocranium: develops from three cartilaginous laminae.
      • Base of the skull.
      • Nasal cavity.
      • Ear region.
      • Forms os occipitale, os temporale, os sphenoidale.
    • Some neurocranial bones incorporate membraneous elements: os parietalis, os temporalis (pars squamosa), os frontale, parts of os occipitalis.
    • Viscerocranium: forms at the 3rd month of embryonic development.
      • Develops from intermembraneous ossification.
      • Forms os zygomaticus, nasale, vomer, maxilla, mandibula, lacrimale, palatinum, tympanic ring.

    Fontanellae

    • Fontanellae: unossified membranes in the cranium.
      • Anterior fontanelle: between two frontal and two parietal bones, closes at 1.5 years.
      • Posterior fontanelle: between the occipital bone and the two parietal bones, ossifies at 1 year.
      • Lateral fontanellae: between frontal, parietal, and temporal bones, ossifies at 3 years.

    Limb Skeleton Development

    • Limb skeleton develops through endochondral ossification under the influence of BMP.

    Newborn Circulation Changes

    • Ductus venosus, ductus arteriosus: their potency is maintained by prostaglandin E2 and I2 influenced by NO.
    • Changes occur after birth:
      • Closing of foramen ovale.
      • Closing of ductus arteriosus --> lig.arteriosus.
      • Umbilical arteries form plica.
      • Umbilical vein --> lig.teres uteri.

    Lymphatic System Development

    • Develops in the 5th week of embryonic development.
    • Lymphatic capillaries: develop from anastomizing perivascular spaces under the influence of VEGF-3.
    • Six lymphatic sacs develop at week 6:
      • Jugular lymph sacs.
      • Retroperitoneal sac.
      • Cisternae chyli.
      • Posterior lymph sacs (transform into sinus lymphaticus iliacus/inguinalis).
    • Collecting lymph vessels: connect these sacs by week 9.
    • Ductus thoracicus: connects cisternae chyli with the junction of v.subclavia and v.jugularis interna.

    Lymph Nodes Development

    • Develop in locations where lymph sacs fold and are infiltrated by a capillary network.
    • Components:
      • Vas afferentes.
      • Subcapsular sinus.
      • Vas efferens.
    • Capsule: formed by surrounding mesenchyme.
    • Germinative centers: appear after first sensitization to antigen.

    Heart Development

    • Critical periods:

      • Fusion of endocardial tubes.
      • Folding of the embryo.
      • Septation of atria and ventricles.
      • Development of valves.
      • Development of truncoconal region.

    • Factors influencing heart development:

      • Dynamic blood pressure.
      • Apoptosis.
      • Migration of neural crest cells.

    Heart and Circulatory Anomalies

    • Open ventricular sept (foramina interventricularis).
    • Arterial sept defects: open foramen ovale.
    • Truncus arteriosus persistance: incomplete septation of truncus arteriosus.
    • Tetralogy of Fallot: hypertrophy of left ventricle, stenosis of pulmonary arteries, ventricular sept defect, right formed aorta.

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    Description

    Explore the fascinating fields of teratology and embryology, focusing on the study of birth defects and the developmental processes of organisms. Learn about various causes of congenital malformations, including genetic and environmental factors. This quiz examines key concepts and terms essential for understanding embryological development and teratogenic impacts.

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