Embryology Flashcards
Gastrulation is when the epiblast and hypoblast form: ectoderm, mesoderm and endoderm.
From what does the mesoderm layer form?
Epiblast
From what layer of embryonic cells is the cardiogenic plate formed?
Until day about day 26, where exactly is this?
Mesderm
The visceral part of the splanchnic mesoderm (above the umbilical vesicle)
Blood from which 2 supplying vessels flows caudally over the inflow tract?
Umbilical and omphalomesenteric veins
Name the 3 layers of the cardiac tube.
- epicardium
- myocardiaium
- endocardium (cardiac jelly inside)
What divides the left and right ventricles in embryo?
Sulcus interventricularis
Day 25 lateral plate mesoderm splits
- What does the visceral layer form with the adjacent endoderm?
- What does the parietal layer form with the adjacent ectoderm?
- splanchnopleura
- somatopleura
When does the head fold occur, causing the previously caudal outflow tract to lie cranially to the inflow tract through a 180 rotation.
Day 25-26
What do the 2 endocardial tubes form when they migrate and fuse together?
A Single primitive heart tube
Name the 5 embryonic structures that arise from the primitive heart tube, cranial to caudal.
- truncus arteriosus
- bulbus cordis
- privitive ventricle
- primitive atria
- sinus venosus
What do the following develop into:
- truncus arteriosus
- bulbus cordis
- privitive ventricle
- primitive atria
- sinus venosus
-truncus arteriosus - ascending aorta and pulmonary trunk
- bulbus cordis - right ventricle
- privitive ventricle - left ventricle
- primitive atria - anterior portions of auricles and both atria
- sinus venosus - post R atrium, SAN and coronary sinus
What are CNCCs and what do they contribute to?
Cardiac Neural Crest Cells
Contribute to Smooth Muscle cells within aortic and pulmonary arteries
The atrioventricular septation in the horizontal plane if formed from what?
AV cushions
Intra-atrial septatation is by…
..forming….
Primary Septum grows down to fuse with AV cushions, the trailing edge breaks down forming the foramen ovale
The septum secundum grows alongside this to form a flap valve over the foramen ovale
Interventricular septation occurs by…
AV septum grows up to meet and fuse with AV cushions to completely divide the L/R Ventricles
How is the AV cushion formed?
From cardiac jelly secreted by myocardium,
Endocardial cells undergo epithelial-mesenchymal transition and populate the jelly to form a cushion
Name 3 Atrial Septal Defects
- Persistant foramen ovale
- Ostium primum defect - primary septum doesnt reach AV cushions
- Ostium secundum defect
Why are ASDs acyanotic?
Inappropriate shunting of blood is only from left side to right side (as higher pressure in left)
Give two types of Ventricular Septal Defects.
Perimembranous - doesnt meet cushions
Muscular - hole in the lower muscular part of septum
Which aortic arch arteries persist in forming the adult structures?
3, 4 and 6
The ductus arteriosus bypasses circulation to the lungs.
What is it called in the adult?
Ligamentum arteriosum
2 OFT-outflow tract defects.
- common truncus
- aortic/pulmonary stenosis die to unequal division of OFT
What is the condition TGA-Transposition of the Great Arteries?
RV connected to aorta,
LV connected to pulmonary trunk
This is cyanotic
What are the features of a Tetralogy of Fallot
- large VSD
- pulmonary stenosis
- RV hypertrophy
- overriding aorta (receives input from both L and R ventricles)
Why may a Tetralogy of Fallot child appear “blue”?
Right to Left shunt is cyanotic
TAPVC - Total Anomalous Pulmonary Venous Connection shunts blood in what direction?
Right to Left (cyanotic)
Why are defects causing holes in septum usually acyanotic?
Because L pressure is higher so shunts blood to right side
