Development of the cardiovascular system

Question 1

As heart tube fuses, 3 layers form:

Answer 1

Endocardium: consists of an endothelium
Myocardium: heart muscle - thick layer of ECM, the cardiac jelly separates myocardium from fused endocardial tubes
Epicardium: Visceral pericardium covering outside of heart tube

Question 2

Initiation of ventricular septation:

Answer 2

Begins with protrusion between right / left ventricular chambers. This protrusion is called the muscular interventricular septum.

Question 3

Completion of septation of ventricles:

Answer 3

Complete with development of membranous ventricular septum.
Allows muscular interventricular septum to fuse with the conotruncal septum.
This completes the interventricular septum.

Question 4

Ventricular septal defects:

Answer 4

Most common heart malformation with the defect most commonly associated with membranous septum

Question 5

Vascular development:
Vasculogenesis facts:

Answer 5

Blood vessel formation.
Develop throughout intraembryonic mesoderm by day 18

Question 6

Vasculogenesis network grows and spreads by 4 main processes:

Answer 6

1.) Continued formation, migration, and coalescence of EPCs (endothelial precursor cells, same as angioblasts) Essentially, EPCs specify and differentiate into endothelial cells, then making vasculogenic cord (blood vessel).
2.) Angiogenesis: the budding and sprouting of new vessels
3.) Vascular intussusception: existing vessels split into new vessels (one big vessel becomes 2 smaller ones)
4.) intercalation of new EPCs into the walls of existing vessels.