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41 Cards in this Set
- Front
- Back
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when does embryonic genome becomes transcriptionally active?
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2-3 days post fertilisation
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when does first mitotic divsion occur?
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26 hrs post fertilisation
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1st 4 mitotic divisions form what structure?
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blastomere
(divisions occur at ~17h intervals) |
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After the 5th mitotic division, the blastomere becomes....
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polarised: trophoblast + inner cell mass
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when does 'hatching'/shedding of zona pellucida occur?
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4-5 GDs
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what is imprinting?
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silencing of one gene copy via covalent modification of DNA (methylation or acetylation)
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When does attachment to the uterine wall occur?
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6 GD
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Name one syndrome caused by a failure of imprinting
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Beckwith-Wiedemann (both copies of IGF2 on chromosome 2 remain active, BIG foetus + prone to tumors)
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Inner cell mass forms 2 layered disc structure after implantation. Name layers.
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Epiblast (dorsal)
Hypoblast (ventral) |
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During which GDs does organogenesis occur?
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20-56+
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what is gastrulation?
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epiblastic cells in disc migrate caudally towards a groove (primitive streak). Forms endoderm
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When does gastrulation occur?
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16GD
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When is neural tube formed?
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18GD
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Describe neural tube formation
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midline groove forms on DORSAL ECTODERM induced by notochordal mesodermal cells.
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which occurs first: gastrulation or neural tube formation?
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gastrulation
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what 2 important paired structures form either side of neural groove?
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neural folds
somites |
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What are somites?
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paired, segmental condensations of mesoderm formed on either side of neural groove
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When does rostral neuropore close?
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23GD
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When does caudal neuropore close?
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26GD
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Failure of rostral neuropore closure results in...
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anencephaly
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Failure of caudal neuropore closure results in...
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spina bifida
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what are 4 main segments of CNS?
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prosencephalon
mesencephalon rhombencephalon spinal cord |
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prosencephalon
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forebrain
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mesencephalon
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midbrain
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rhombencephalon
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hindbrain
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What is aniridia?
What is gene mutation implicated? |
failure of iris formation
PAX6 transcription factor |
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which gene is known to influence somite positioning
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Hox
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3rd ventricle formed by which CNS embryological segment?
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prosencephalon: telencephalon + diencephalon
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Which CNS segment forms optic cups
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diencephalon (D1)
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When does optic envaginations occur?
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28GD
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What segement of CNS forms thalamus + hypothalamus
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diencephalon D2
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Which part of pituitary is formed by neural tube?
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posterior (neurohypophysis)
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What is holoprosencephaly?
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failure of cerebral hemispher separation (normally occurs 32GD)
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what produces the repeated pattern of spinal nerve roots?
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somites
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Gut tube is lined by what cell type?
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endoderm
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When does respiratory diverticulum first appear?
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26 GD
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Does respiratory diverticulum appear ventrally or dorsally?
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ventral (think trachea ventral to esophagus)
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airway development is called
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branching morphogenesis
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mesonephros forms what organ?
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kidneys
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what embryological layer forms the mesonephros?
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intermediate mesoderm
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what connects mesonephros to the cloaca?
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Wolffian (mesonephric) duct
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