Embrio 2.1: 4th week Flashcards
3° et 4° arc and what they generate? Clinical Application?
Les 3° et 4° arcs donneront les cellules glandulaires des parathyroïdes et le thymus.
Les vaisseaux de ces arcs formeront la crosse de l’aorte et les gros vaisseaux de la base du coeur et du cou
Exam: Syndrome diGorge when malformation
What does the 1st arc form?
It forms the **mandibule ** and orreilles (exam)
syndrorne de DiGeorge
anomalie du développement des 3° et 4° arcs which leads to
** absence de thymus, absence de parathyroide, et malformations cardio-aortiques **
Sillons naso-labiaux
Les sillons naso-labiaux se forment entre 31 et 33 jours lorsque les fentes naso-labiales fusionnent.
Cette fusion combine les portions latérales des lèvres avec le bourgeon labial médian, formant le philtre nasal.
À 48 jours, les bourgeons nasaux internes fusionnent ensemble et avec le maxillaire. Ces lignes de fusion forment deux crêtes de peau, de chaque côté du philtre nasal.
Une fusion anormale peut causer une fente labiale, unilatérale ou bilatérale, qui peut également être associée à une fente palatine.
What can cause fente palatine?
Hypoplasia of lateral palatine plaques (see page 81)
If there aren’t enought cells to close towards the plaque palatine mediane then the closue wont be done properly
Malformation of the tongue that prevents the plates from fusing properly
A potential rupture after fusion
fente labiale vs fente palatine
fente labiale: Only malformation in lips
fente palatine: Lips and the bone behind (palate)
What is syndrome de Van der Woude, and what is special?
A malformation that results in fentes naso-labio-palatines,
Special:
**transmission autosomale dominante. **
Which members will develop faster?
The superior limbs (membres) are the first ones to develop
Describe the process of angiogenesis
The the process of angiogenesis, which is the formation of new blood vessels, needs to start very early to meet the oxygen needs of the fetus and their lack of nutritional reserves.
The first vessels are extra-embryonic and come from mesoblastic cells of the embryonic stalk, the placenta, and the yolk sac. These mesoblastic cells differentiate into angioblasts around the 14th day after conception. The intra-embryonic vessels appear 2 days later. These two circulations develop independently, and around day 21, they merge at the level of the embryonic stalk to form the primitive circulatory system.
Cardaic formation and genes (overview)
1 gene can be implicated in multiple parts of the formation
1 anomaly can arise due to many genes being mutated or 1 single gene
Anomalie du premier arc branchial, avec excroissance polypoide, communément appelée hamartome pré-auriculaire. Cette malformation est relativement fréquente; elle est rarement associée à des malformations rénales. Why?
The concept of 1 gene can be used in different places of develompent.
If a gene has caused an issue at the ears it is not unlikely that aother organ might use that gene even if partly (like the heart).
Where do hematopetic cells come from?
A) Cells next to the Heuser’s membrane come together and change into blood islands.
B) Spaces or ‘lights’ form within these blood islands.
C) Some cells from the primitive endothelium (the inner lining of blood vessels) differentiate into primitive hematopoietic cells. These cells stick to the endothelium, while their daughter cells are released into the bloodstream.
D) The blood vessels merge, leading to an expansion of the blood vessel network.
E) The cells lining the vessels change into endothelial cells, which stimulate the nearby mesenchyme (a type of tissue) to form the walls of the blood vessels
Circulation intra-uterine
Blood comes from the placenta through the ombilical veine, through the inferior vena cava
This is the oxygenated blood that will go to the now-developed heart
The blood flows into the right atrium, into the left atrium through foramen ovale, into the aortic crosse.
From the aortic crosse, there is a aortic isthme that contracts in order to keep the circulation towards the head when blood is oxygenated. In low oxygenation conditions, teh stenosis is gone and the blood can flow towards the ombilical arteries to be sent to the mother for re-oxygenation. (this isthme will disapear when born to allow the blood to go to inferior members)
The blood that went to the head circles back (deoxygenated) to enter the right atrium, right ventricle and then through the canal arteriel to be sent to the mother for re-oxygenation
What happens to the heart after the baby starts breathing?
See diagram
In utero the foramen oval is open
Once the blood has fed the brain it comes back. This blood enters the right atrium via the superior vena cava, then moves down to the right ventricle.
From the right ventricle, the blood is pushed through the pulmonary artery.
At this point, the blood can either travel through the left and right pulmonary arteries or pass through the arterial canal. This decision is based on pressure.
Given the high resistance in the lungs in utero, most of the blood will pass through the arterial canal.
However, once the baby starts breathing, the resistance in the lungs drops significantly, almost to zero.
This change allows the blood to flow into the pulmonary arteries instead of the arterial canal.
The blood then moves into the left atrium and left ventricle, generating a high pressure.
This high pressure keeps the foramen ovale closed until it eventually fuses together and permanently closes over time.
The arterial canal also closes over time, as the blood prefers the path through the pulmonary arteries.
The aortic isthme also disappears allowing the blood to travel via the descending aorta towards inferior limbs
What are coussin endocardiaque?
These are what will form the auriculo-ventricular septum separating the auriculo-ventriculaire canal into the tricuspid and mitral canals (left and right heart)
The CAV will then have projections on top and bottom in order to separate the ventricles and aortas
