3: Embryology Flashcards
What are the cellular processes that happen in embryology?
They overall function the exact same as other cells
Everything also happens via
- proliferation
- differentiation
- reorganisation and
- apoptosis
What happes during the first two month of human development?
Mainly lay down of all important organs
After 8 Weeks: mainly growth and elaboration of the structures that develop during the first two months
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What happens to the fertilised egg in the Preimplantation state?
Preimplantation about 6 days
- Serious of cleavage –> Every time doubeling the cell number
- Egg develops into a Morula (=ball of undifferentiated cells)
- Differentiates so outer cells differ from inner cells
- Develops into a Balastocyte
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Explain the structure of a Blastocyst
structure that has an
outer layer of trophectoderm (surrounded by zona pellucida)
, an inner cell mass,
and a fluid-filled cavity.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/303/459/348/a_image_thumb.png?1582475460)
When does implantation take place?
How does is happen?
The blastocyst seperates from outer zona pellucida and merges with the uterine lining (finished at day 10)
How does a Blastocyst differentate further (during implantation)?
The inner cell mass ot blastocyte becoms a bilayer disk, composed of
- hypoblast and
- epiblast cells
–> This bilayer disk gives rise to all the tissues of the human fetus
What is gastulation?
When does it occur?
14-18 days postfertilisation
which converts the bilayer of hypoblast and epiblast cells into a trilaminar embryo,
containing the three layers of Germ Cells
- (Ectoderm,
- Mesoderm and
- Endoderm),
![](https://s3.amazonaws.com/brainscape-prod/system/cm/303/460/388/a_image_thumb.png?1582476288)
Explain the process of gastrolation
- Epiblast cells proliferate and differentiate to form mesoderm cells
- These cells move to space between hypoblast and epiblast
- Mesoderm Cells differentiate and replace the hyoblast cells with endoderm cells
![](https://s3.amazonaws.com/brainscape-prod/system/cm/303/460/564/a_image_thumb.png?1582476465)
What kind of tissues to mesoderm cells differntiate?
muscles, blood, skeleton, heart and kidney
What kind of tissues to ectoderm cells differntiate to?
Skin and CNS
Which tissues to endoderm differentiate to?
Into
- Gut
- Lung
- Liver
But: Muscular and vascular tissue are generally of mesodermal origin, so tissues are normally a mixture of germ layer types (e.g. muscle in the skin and gut).
What is Neurolation
What is it controlled by?
It is formation of the Neural tube (Brain + Spinal Chord) controlled by the Notocord (in the mesoderm)
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Explain the earyl process of neurolation
- Development of the neural plate
- It develops two folds
- They grow and meet over the neural groove
- to form the neural tube
![](https://s3.amazonaws.com/brainscape-prod/system/cm/303/739/598/a_image_thumb.png?1582644763)
When does the neural tube close?
Closing continues in Week four
- Cranial End about 22 days
- Rostral End about 23/24 days
![](https://s3.amazonaws.com/brainscape-prod/system/cm/303/739/834/a_image_thumb.png?1582644899)
Explain the process of embryological folding
When does this happen?
3-4 Weeks
- Tissues fold laterally and fuse in the ventral midline
- In anteroposterior direction
- Folds the primordial germ cells (PGCs) from caudal end into hindgut and heart progenitor cells under head of embryo
![](https://s3.amazonaws.com/brainscape-prod/system/cm/303/740/157/a_image_thumb.png?1582645201)