68 Questions
Which gene is involved in CNS development and anterior-posterior limb axis patterning?
Sonic hedgehog (SHH)
Which gene is involved in dorsal-ventral limb axis patterning?
Wnt-7
Which gene contributes to proximal-distal limb outgrowth?
Fibroblast growth factor (FGF)
What is the result of mutations in Sonic hedgehog (SHH) gene?
Holoprosencephaly
When does primitive streak formation occur during early embryonic development?
Day 14
When does ectoderm, mesoderm, and endoderm formation occur during early embryonic development?
Week 3
What is the key developmental stage when notochord induces neural plate and neurulation?
Gastrulation and formation of trilaminar embryonic disc in week 3
When does genitalia differentiation occur during embryonic development?
Week 8
Which of the following is NOT a derivative of the ectoderm?
Parotid gland
Which of the following structures is derived from the mesoderm?
Liver
Which of the following is a derivative of the neural tube?
Pineal gland
Which of the following is a derivative of the neural crest?
Schwann cells
Which of the following is a derivative of the endoderm?
Thyroid follicular cells
Which structure is derived from the surface ectoderm?
Sweat glands
Which of the following is NOT a derivative of the mesoderm?
Microglia
Which structure is derived from the notochord?
Nucleus pulposus
Which of the following is a derivative of the mesoderm but NOT the endoderm?
Urethra
Which of the following is derived from the neural tube?
PNS ganglia
Which of the following structures is derived from the surface ectoderm?
Epidermis
Which of the following is a derivative of the mesoderm but NOT the endoderm?
Muscle
When does primitive streak formation occur during early embryonic development?
During gastrulation
Which of the following is a derivative of the neural crest?
Melanocytes
Which structure is derived from the notochord?
Nucleus pulposus
Which of the following is derived from the neural tube?
Spinal cord
When does genitalia differentiation occur during embryonic development?
During sexual maturation
Which of the following is NOT a derivative of the ectoderm?
Muscle
Which of the following is a derivative of the endoderm?
Liver
Which of the following is derived from the neural tube?
Spinal cord
Which type of error in morphogenesis involves the absence of an organ due to the absence of primordial tissue?
Agenesis
Which type of error in morphogenesis involves the absence of an organ despite the presence of primordial tissue?
Aplasia
Which type of error in morphogenesis involves incomplete organ development with primordial tissue present?
Hypoplasia
Which type of error in morphogenesis involves a secondary breakdown of tissue with normal developmental potential?
Disruption
Which type of error in morphogenesis involves extrinsic mechanical distortion of tissues during the fetal period?
Deformation
Which type of error in morphogenesis involves an intrinsic developmental defect occurring during the embryonic period?
Malformation
Which type of error in morphogenesis results from a single primary embryologic event?
Sequence
Which specific syndrome associated with errors in morphogenesis can cause intellectual disability, facial abnormalities, limb dislocation, and heart defects?
Fetal alcohol syndrome
Which specific syndrome associated with errors in morphogenesis involves maternal substance use during pregnancy and affects the central nervous system, autonomic nervous system, and gastrointestinal systems of newborns?
Neonatal abstinence syndrome
Which type of error in morphogenesis involves a disturbance of tissues that develop in a contiguous physical space?
Field defect
Which medication taken during pregnancy can cause renal failure, oligohydramnios, and hypocalvaria in the fetus?
ACE inhibitors
Which substance used during pregnancy can cause fetal alcohol syndrome in the newborn?
Alcohol
Which medication taken during pregnancy can cause neural tube defects, cardiac defects, cleft palate, and skeletal abnormalities in the fetus?
Antiepileptic drugs
Which medication taken during pregnancy can cause vaginal clear cell adenocarcinoma and congenital Müllerian anomalies in the fetus?
Diethylstilbestrol
Which medication taken during pregnancy can cause cartilage damage in the fetus?
Fluoroquinolones
Which medication taken during pregnancy can cause craniofacial, CNS, cardiac, and thymic defects in the fetus?
Isotretinoin
Which medication taken during pregnancy can cause Ebstein anomaly in the fetus?
Lithium
Which medication taken during pregnancy can cause aplasia cutis congenita in the fetus?
Methimazole
Which medication taken during pregnancy can cause discolored teeth and inhibited bone growth in the fetus?
Tetracyclines
Which medication taken during pregnancy can cause limb defects in the fetus?
Thalidomide
Which medication taken during pregnancy can cause ototoxicity in the fetus?
Aminoglycosides
Which substance used during pregnancy can cause fetal alcohol syndrome?
Alcohol
Which medication taken during pregnancy can cause craniofacial, CNS, cardiac, and thymic defects in the fetus?
Isotretinoin
Which medication taken during pregnancy can cause neural tube defects, cardiac defects, cleft palate, and skeletal abnormalities in the fetus?
Folate antagonists
Which medication taken during pregnancy can cause Ebstein anomaly in the fetus?
Lithium
Which medication taken during pregnancy can cause aplasia cutis congenita in the fetus?
Methimazole
Which medication taken during pregnancy can cause limb defects in the fetus?
Thalidomide
Which substance used during pregnancy can cause preterm birth, low birth weight, fetal growth restriction, and sudden infant death syndrome (SIDS)?
Tobacco smoking
Which factor during pregnancy can cause congenital hypothyroidism in the fetus?
Iodine lack
Which factor during pregnancy can cause caudal regression syndrome, cardiac defects, neural tube defects, and macrosomia in the fetus?
Maternal diabetes
Which layer of the chorionic villi creates cells?
Cytotrophoblast
Which layer of the chorionic villi synthesizes and secretes hormones, such as hCG?
Syncytiotrophoblast
What is the chance of attack by the maternal immune system for the syncytiotrophoblast?
0%
Where is maternal blood found in the placenta?
Decidua basalis
What is the main function of the umbilical vein?
Oxygen-rich blood transport
What is the main function of the umbilical arteries?
Oxygen-poor blood transport
What is the main function of the amnion?
Maternal blood circulation
What is the main function of the chorion?
Fetal blood circulation
What is the main function of the amniotic fluid?
Intramembranous absorption
What can cause polyhydramnios, characterized by too much amniotic fluid?
Multifetal gestation
Study Notes
Embryonic Development
- Sonic hedgehog (SHH) gene is involved in CNS development and anterior-posterior limb axis patterning.
- Genes involved in dorsal-ventral limb axis patterning are Wnt and BMP.
- Genes involved in proximal-distal limb outgrowth are FGF and Wnt.
Mutations and Effects
- Mutations in Sonic hedgehog (SHH) gene result in holoprosencephaly.
- Primitive streak formation occurs during early embryonic development, around day 14-15.
- Ectoderm, mesoderm, and endoderm formation occur during early embryonic development, around day 3-4.
- Notochord induces neural plate and neurulation during early embryonic development, around day 21-22.
- Genitalia differentiation occurs during embryonic development, around week 9-12.
Derivatives of Germ Layers
- Ectoderm derivatives include skin, nervous system, sensory organs, and mouth lining.
- Mesoderm derivatives include muscles, bones, kidneys, and reproductive organs.
- Endoderm derivatives include respiratory, gastrointestinal, and urinary systems.
- Neural tube derivatives include brain, spinal cord, and peripheral nerves.
- Neural crest derivatives include melanocytes, adrenal glands, and cranial nerve ganglia.
Errors in Morphogenesis
- Agensis: absence of an organ due to the absence of primordial tissue.
- Aplasia: absence of an organ despite the presence of primordial tissue.
- Hypoplasia: incomplete organ development with primordial tissue present.
- Dysplasia: secondary breakdown of tissue with normal developmental potential.
- Deformation: extrinsic mechanical distortion of tissues during the fetal period.
- Malformation: intrinsic developmental defect occurring during the embryonic period.
- Sequence: results from a single primary embryologic event.
Syndromes Associated with Errors in Morphogenesis
- Fetal alcohol syndrome: characterized by intellectual disability, facial abnormalities, limb dislocation, and heart defects.
- Diethylstilbestrol (DES) syndrome: affects the central nervous system, autonomic nervous system, and gastrointestinal systems of newborns.
Teratogens and Effects
- Isotretinoin (Accutane) can cause renal failure, oligohydramnios, and hypocalvaria.
- Ethanol (alcohol) can cause fetal alcohol syndrome.
- Retinoic acid can cause neural tube defects, cardiac defects, cleft palate, and skeletal abnormalities.
- Diethylstilbestrol (DES) can cause vaginal clear cell adenocarcinoma and congenital Müllerian anomalies.
- Tetracycline can cause cartilage damage.
- Warfarin can cause craniofacial, CNS, cardiac, and thymic defects.
- Lithium can cause Ebstein anomaly.
- Methotrexate can cause aplasia cutis congenita.
- Tetracycline can cause discolored teeth and inhibited bone growth.
- Thalidomide can cause limb defects.
- Streptomycin can cause ototoxicity.
Placenta and Amniotic Fluid
- The syncytiotrophoblast layer of the chorionic villi creates cells.
- The cytotrophoblast layer of the chorionic villi synthesizes and secretes hormones, such as hCG.
- The chance of attack by the maternal immune system for the syncytiotrophoblast is high.
- Maternal blood is found in the intervillous space of the placenta.
- The main function of the umbilical vein is to bring oxygenated blood from the placenta to the fetus.
- The main function of the umbilical arteries is to remove deoxygenated blood from the fetus to the placenta.
- The main function of the amnion is to provide a protective environment for the fetus.
- The main function of the chorion is to provide a site for maternal-fetal gas exchange.
- The main function of the amniotic fluid is to provide a buffer against mechanical shocks and to facilitate fetal movement.
- Polyhydramnios can be caused by diabetes, multiple pregnancies, and congenital anomalies.
Test your knowledge on Homeobox (HOX) genes and Sonic hedgehog (SHH) in this quiz! Learn about their functions, locations of production, and the impact of mutations. Discover how isotretinoin affects HOX gene expression and the consequences of SHH mutations.
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