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43 Cards in this Set
- Front
- Back
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Beginning of the third week, ? begins to transform the bilaminar disc into a trilaminar germ disc composed of three germinative layers.
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Gastrulation
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What are the three germinative / precursor layers of the trilaminar germ disc?
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Ectoderm
mesoderm Endoderm |
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When week does gastrulation occur?
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3rd week
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When is the Embryonic Period?
Also known as the period of ? |
3rd week - 8th week
organogenesis |
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By what week can you start determining the orientation of the bilaminar disc?
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3rd week
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What thickens to form the NEURAL PLATE?
hint: it overlies the notochord |
Ectoderm
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Lateral edges of the neural plate curve upward forming Neural Folds with a central ?
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neural groove
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At what future structure do Neural Folds begin to fuse together?
This fusion of Neural Folds forms the ? ? and ? |
Future Neck
Neural tube Future brain Spinal Cord |
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? is the cranial opening of the neural tube.
It is "closed" / fused at what day? Disruption of closure will cause what defect? |
Anterior/Rostral neuropore
Day 25 Anencephaly/encephalocele |
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What is the caudal opening of the neural tube?
Closure of this structure occurs on what day? Disruption of closure produces what defect? |
posterior/caudal neuropore
Day 27 meningomyelocele |
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Cells at the "crest" of the neural folds detach and migrate as the fold fuse. These cells called ? migrate throughout the body to provide intermediate neural like cells to a variety of tissue
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Neural Crest Cells
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What are the 3 paired ectodermal thickenings associated with the developing brain?
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Lens Placodes
Otic Placodes Nasal Placodes |
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Two expansions of the cranial neural tube, ? induce thickening of the overlying ? to the paired lens placodes
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optic cups
Ectoderm |
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? invaginate to form otic vesicles and ultimately the inner ear.
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Otic Placodes
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? form nasal pits and ultimately nasal cavities
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Nasal placodes
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The ectoderm will give rise to what 5 things?
PANNS |
Portions of the sensory epithelium (ear, nose and eye)
Nervous system Neural Crest Cells Skin and adnexal structures Anterior Pituitary |
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Mesodermal differentitation is initially loose and condensation occurs on day ?
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day 17
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? mesoderm is adjacent tot he developing neural tube.
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Paraxial mesoderm
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Cranial to caudal segmentation of the Paraxial Mesoderm is called ?
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Somites
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Subsequent reorganization and differentiation of somites into 3 tissues of the region::
What are they? |
Sclerotome
Myotome Dermatome |
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What is Sclerotome?
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ventral ::
surrounds the developing neural tube and notochord => forms Vertebra (skeleton) |
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What is Myotome?
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develops into MUSCULATURE of the region
=> forms muscle |
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What is Dermatome?
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dorsal
dermis of the overlying skin => soft tissue |
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What are the number of somites that develop in the...
Occipital? Cervical? Thoracic? Lumbar? Sacral? Coccygeal? |
occipital = 4
cervical = 8 thoracic = 12 lumbar = 5 sacral = 5 Coccygeal = 8-10 |
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What are the 3 types of Mesoderm?
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Paraxial mesoderm => Somites
Intermediate mesoderm => urogenital tissue (kidneys and genital system) Lateral Plate Mesoderm => somatic/parietal mesoderm & Visceral/splanchnic mesoderm |
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Paraxial mesoderm forms
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Somites
which give rise to -sclerotome -myotome -dermatome |
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Intermediate mesoderm gives rise to?
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kidneys and genital system
urogenital tissue |
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Lateral plate mesoderm gives rise to?
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outer layer - Somatic/parietal mesoderm
Lines the inner aspects of the Body Wall Inner layer - Visceral/splanchnic mesoderm covers the developing GI system and associated organs (viscera) |
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Blood Islands form within what layer?
Describe the blood island formation |
Mesoderm
Outer cells => sacs of primitive ENDOTHELIUM => form rudimentary network Central cells => blood cells |
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What vessels coalesce to form the primitive fetal vascular network?
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Vessels in the...
yolk sac embryo developing placenta |
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What are the 4 Key landmarks in the folding of the Trilaminar Embryonic Disc?
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Septum Transversum
Cardiogenic Region Oropharyngeal Membrane Cloacal membrane |
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Curves the embryo along the cranial-caudal axis
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Neuralation
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? helps fold the lateral aspects of the embryo during folding of the trilaminar embryonic disc.
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Mesodermal differentiation (somites/lateral plate mesoderm)
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? is the VENTRAL site where the cranial, caudal and later folds join.
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Umbilicus
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The complicated folding is vulnerable to drugs or environmental factors that change ? , ? and ?
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Migration rates
Cell proliferation cell adhesion |
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By the end of ? week (? month) the form of the embryo is established.
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8 weeks / 2 months
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What are the derivatives of the Endoderm?
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GI tract
Associated Organs foregut - thyroid, tonsils, thymus & parathyroid, lung, liver & pancreas Midgut - none Hindgut - Bladder |
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? interconnects the midgut porition of the primitive gut with the remaining extra-embryonic yolk sac.
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Vitelline Duct
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Folding the embryo incorporates teh epiblast-derived ? of the yolk sac into the embryo as the ?
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Endoderm
Primitive Gut |
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The cranial region incorporates the ?
Caudal folds incorporate the ? Lateral folds assist with PRIMITIVE gut formation |
cranial = Foregut
Caudal = Hindgut |
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Where is the bladder formed from?
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Hindgut
Endoderm |
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The organ and the body shape are established during ?
This is called the ? period |
3-8 weeks
Embryonic Period |
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Chemicals that later the balance and produce malformations are called ?
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Teratogens
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