Cardiac Embrology Flashcards
When does the primitive, muscular heart tube begin having some contractability?
as early as the 24-24th day
The 1st presentation of the CV system is a condensation of splanchnic lateral plate mesoderm, located near the oropharyngeal membrane, and is called?
The cardiogenic mesoderm
Describe the formation of the single primitive heart tube starting from the condensation of the cardiogenic mesoderm
- Cardiogenic mesoderm condenses, hollows out, and forms a horse-shoe shaped tube.
- The horse-shoe shaped tube splits into the left and right heart tubes
- Lateral body folding -> fusion of L & R heart tubes creating the primitive single heart tube
When does the single primitive heart tube migrate from the mouth region down to the thoracic region?
After Cranial-to-caudal body folding
- during the 4th week
What are the five divisions of the embryonic heart tube (primitive heart tube) (from cranial to caudal?)
- Truncus arteriosus
- Bulbus cordis
- Primitive ventricle
- Primitive atrium
- Sinus Venosus
Which end of the embryonic heart tube represents the arterial outflow? The venous inflow?
Cranial = Arterial outflow (includes primitive ventricles)
Caudal = Venous inflow (includes primitive atria)
Describe the looping and folding events that transform the heart tube into the more definitive adult form
a. The venous (atrial) end moves: Posterior, superior, and to the Right
b. The Arterial (truncal and Ventricle) end moves anterior, inferior and to the left
Adult structures arising from the Truncus arteriosus?
- Aorta
- Pulmonary trunk
- Semilunar valves
Adult structures arising from the bulbus cordis?
- Conus Arteriosus (Smooth part of RIGHT ventricle)
2. Aortic Vestibule (Smooth part of LEFT ventricle)
Adult structures arising from the primitive ventricle
Trabeculated parts of the left and right ventricles
Adult structures arising from the primitive atrium
Pectinate muscles of the left and right artria (i.e. The auricles)
Adult structures arising from the Sinus Venosus
Right side -> Sinus Venarum (smooth part of RA)
Left side -> Coronary Sinus and oblique vein of LA
What part of the heart tube DOES NOT undergo septation?
The Sinus Venosus
- the other 4 division form septa
What causes pressure on the right side of the heart to be greater than the left side of the heart during fetal circulation?
- Umbilical blood flow entering the RA via the IVC and SCV
2. High pulmonary resistance because the pulmonary circulation is closed
The Ductuc Venosus bypasses what organ?
The liver
- by redirecting it to the IVC
The Foramen Ovale bypasses what organ?
The lungs
- redirects blood from the RA to the LA
The Ductus Arteriosus bypasses what organ?
The Lungs
- by bypassing the pulmonary arteries
The adult remnant of the Ductus arteriosus?
Ligament arteriosum
The adult remnant of the Umbilical vein and arteries?
Vein = Round ligament of liver (ligamentum teres)
Arteries (2) = Medial umbilical ligaments
Adult remnant of the foramen ovale?
Fossa ovalis
What parts of the CV system are dependent on neural crest cell migration?
- Truncus arteriosus
- Endocardial cushions
- failure of NC cells to migrate lead to septation defects
What is the endocardial cushion?
A mass of mesoderm located in the center of embryonic heart tube
During atrial septation, from which direction does the septum primum grow?
Downward from the roof of the atria
- the eventualy fusion of the spetum primum with the Endocardial cushion is dependent on NC cell migration
How is the foramen secundum formed?
via apoptosis of the upper aspect of the spetum primum
