What process starts at day 14?
Gastrulation
Explain how the process of gastrulation starts
Primitive grove separates the epiblast into two halves
What direction does the primitive grove divide?
From the caudal to cranial end
What change occurs when the disk elongates?
Epiblast becomes narrow at the caudal and thinker at the cranial end
What makes the up primitive streak?
Primitive groove, primitive pit and primitive node
What happens to the cells that migrate and dive through the primitive groove?
Differentiate to form new cell layers
What three layers make up the trilaminar disk?
Embryonic endoderm, embryonic mesoderm and embryonic ectoderm
What layer do the cells that dive the deepest into the primitive groove become?
Embryonic endoderm
What does the cranial bilaminar region eventually form?
Mouth
What does the caudal bilaminar region eventually form?
Anus and genitourinary tract
How are the bilaminar regions formed?
Two layers of the ectoderm layer push ventrally to fuse with the endoderm layer excluding the mesoderm layer
How is a notochord formed?
Group of mesoderm cells form a solid rod
What is meant by a notochord being transient?
Doesn’t exist as a structure in adults
What does the notochord contribute to in adults?
Nucleus pulpous which is the belly like centre of the vertebral disks
What are the roles of the notochord?
Influences embryo folding and secretes sonic hedgehog protein
What is the role of sonic hedgehog proteins?
Cell awareness in three dimensional space
What three types of mesoderm are created when the cells around the notochord differentiate?
Paraxial, intermediate and lateral
Explain the process of neurulation
Notochord stimulates the cells in the ectoderm layer to thicken and form the neural plate which depends to form the neural groove with neural folds which pinch of to form the neural tube
Where is the neural tube located?
Between the mesoderm and ectoderm
How does the notochord help with cell awareness?
Cells closer to the notochord receive more SHH helping them recognise their location
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Male reproductive system26
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Female reproductive system28
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Fertilisation16
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Human development days 4-76
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Human development week 26
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Development of twins8
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Human development week 320
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Sealing complications6
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Growth hormone16
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Development of the reproductive system40
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Human embryology and congenital abnormalities36
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Fertilisation14
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From the blastocyst to the neural tube22
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A sense of proportion10
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Sex determination20
