4th week of development Flashcards
What are the two main events during the 4rth week?
Neurulation is complete and we have a cylindrical embryo. (3D structure)
What are responsible for the factors released by the notochord?
The transformation of the ectoderm into neural plate.
Why does not all the ectoderm transforms to neural tissue?
Due to inhibiton of growth (BMP-4) of neural plate.
Lateral boundary stablished
When does the neural tube is completely formed?
In the 4rth week.
By day 28 the neural tube is completely invaginated.
What does the neural tube gives rise to?
The Central Nervous System (CNS)
Brain and spinal chord.
What forms the neural crest cells?
The PNS.
Mostly, not all.
From what type of layer do somites proceed?
From the paraxial mesoderm
The mesoderm closest to the notpchprd
Are somites internal or external sructures?
Internal structures
Have an ectoderm layer on top.
In what are transformed neural crest cells?
Into mesencymal cells
With the ability to growth and proliferate.
What mesoderm surrounds the gut tube (yolk sac)?
Splanchnic mesoderm
To what will the intraembryonic body cavity (coelom) will give rise?
To the thoracic and abdominal cavities.
From where is derived the allantois?
From the posterior wall of the yolk sac.
The allantois will give rise to the urinary bladder and with the connecting stalk will form the umbilical cord.
What are some structures present in the 4th week?
The lens and otic placode, the pharyngeal arches and the somites.
What’s Ectopia Cordis?
The heart outside the embryo.
