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58 Cards in this Set
- Front
- Back
When is an embryo referred to as a fetus? Why?
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After 8 weeks b/c organoogenesis is complete.
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Zygote
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Fertilized Cell
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Blastomeres
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Daughter cells that form after fertilization usually 16-32
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Morula
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Collection of blastomeres
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Where is the ovum fertilized? Where does it go after fertilization?
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Ovum fertilized in ampulla of uterine tube
Travels to the uterus after fertilization |
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Blastocyst Cavity
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Fluid-filled area found in the morula
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Blastocyst
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Term that refers to a morula w/a blastocyst cavity
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Outer Cell Layer/Trophoblast
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Gives rise to embryonic part of placenta and is in blastocyst
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Inner Cell Layer/Embryoblast
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Gives rise to whole embryo/embryo proper, forms in blastocyst
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Embryonic Pole
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Designated side of the blastocyst where the inner cell mass/embryoplast moves
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Zona Pellucida
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Outer protective layer of the blastocyst lost during dev't
Allows rapid growth to occur |
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Outer Syncytiotrophoblast
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One of the trophoblast differentiated layers, invades uterine wall, produces HCG
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Inner Cytotrophoblast
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One of the trophoblast differentiated layers, produces new cells
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Hypoblast
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Cell layer that forms after the first week along the embryoblast facing the blastocyst, below epiblast, cells produce extra-embyronic mesoderm
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Ovum
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Fertilized Oocyte
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What are the 2 layers that the inner cell mass becomes?
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1. Epiblast
2. Hypoblast |
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Epiblast
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One of layers formed from the inner cell mass, above hypoblast, gives rise to the fetus
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Bilaminar Germ (Embryonic) Disc
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Made of the epiblast and hypoblast
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Amniotic Cavity
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Cavity that forms within the epiblast, filled with amniotic fluid, lined with amnioblasts (specialized epiblast cells)
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What ruptures signaling the onset of labor?
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Amniotic cavity
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Primary Yolk Sac
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Below hypoblast layer, contains fluid
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Extraembryonic Mesoderm
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Loose connective tissue outside the primary yolk sac, vesicles form here
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Extraembryonic Coelom
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Separates the extraembryonic mesoderm into two layers:
1. Extraembryonic splachnic mesoderm 2. Extraembyronic somatic mesoderm |
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Where do the epiblast and hypoblast come from?
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Inner cell mass/embyroblast
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What is the bilaminar germ disc comprised of?
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Epiblast and hypoblast
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What cavity forms in the epiblast?
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Amniotic cavity filled with amniotic fluid
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Cells from what layer give rise to the extraembyonic mesoderm?
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Hypoblast
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What is another name for the primary yolk sac?
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Exocoelomic cavity
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What is the difference b/w the exocoelomic cavity and the extraembyronic coelom?
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Exocoelomic cavity = primary yolk sac
Extraembryonic coelom = formed from the extraembryonic mesoderm and separates the mesoderm |
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Chorionic Cavity
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Renamed term for extraembryonic coelum
Enlarges to pinch off primary sac to give rise to the 2ndary yolk sac |
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Oropharyngeal Membrane
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Future mouth, forms at end of bilaminar disc where epiblast + hypoblast cells become attached
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Cloacal Membrane
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Future anus, forms at end of bilaminar disc where epiblast + hypoblast cells become attached
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Primitive Streak
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At the caudal (posterior) end of bilaminar disc, depression is called primitive groove
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Primitive Node
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At the cranial (anterior) end of bilaminar disc, depression is called primitive pit
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Gastrulation
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Epiblast cells migrate through the primitive groove and pit into area underneath (ventral), displacing existing hypoblast cells to form new hypoblast layer (embryonic endoderm)
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Embryonic Endoderm
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Formed during gastrulation when epiblast cells move ventrally from primitive groove and pit
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Intraembryonic Mesoderm
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Eventually forms notochord, between the epiblast and hypoblast layers during gastrulation
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Embryonic Ectoderm
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Cells that stay in the epiblast during gastrulation
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How is the notochordal process initiated?
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Cells migrate from the epiblast through the primitive pit and move in a cranial (anterior) direction in the mesodermal layer until it reaches the oropharyngeal membrane
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____ will form into the notochord?
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Notochordal process
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How is the neural plate formed?
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Formation of notochord induces the overlying ectoderm to thicken leading to formation of the neural plate
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Formation of the neural plate leads to formation of a specialized ectoderm referred to as?
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Neuroectoderm
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Neurulation
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Formation of the neural plate, folding of plate into neural folds and closure of folds to form the neural tube
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Neural Tube
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Forms during neurulation, gives rise to the CNS
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Hypoblast cells form what layer?
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Embyronic endoderm
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Oropharyngeal Membrane
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Cranial/Anterior end during gastrulation, future mouth
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Cloacal Membrane
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Caudal/Posterior end during gastrulation, future anus
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Which layer does the notochord arise from?
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Intraembryonic mesoderm
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The intraembyronic mesoderm differentiates into which 3 layers?
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1. Paraxial Mesoderm
2. Intermediate Mesoderm 3. Lateral Plate Mesoderm |
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Intermediate mesoderm gives rise to?
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Urogenital system
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Lateral plate mesoderm is involved in what?
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Body Folding
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How are somites formed?
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By paraxial mesoderm differentiation + segmentation
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Sclerotome
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Portion of somite, gives rise to bone and cartilage (forming vertebrae + ribs)
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After the neural tube is formed, what happens?
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The tube drops beneath the ectodermal layer, closure of the cranial neuropore and then caudal neuropore in a zipper-like fashion
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Neural Crest Cells
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Along edge of neural folds, detach themselves and migrate to body areas
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What does the 2ndary yolk sac become?
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GI tract + derivatives
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Lateral plate mesoderm divides into which 2 layers?
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1. Somatic/parietal layer lining future body wall
2. Splanchnic/visceral layer lining outside of 2ndary yolk sac |
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GI tract is derived from which structure?
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Yolk sac
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