"concurrently, atrioventricular endocardial cushions develop within the heart."
"growth of the atria facilitates the formation of another partition, the septum secundum. This similarly grows from the atrial roof but does not completely divide the two cavities - the space it leaves is the foramen ovale."
"the surrounding ventricular myocardium disappears (either through erosion from blood flow or apoptosis) such that these mesenchymal proliferations are attached to the ventricles via thin muscular tissue."
"septum primum grows down towards these cushions – the space between these structures is the ostium primum and allows inter-atrial communication"
"apoptosis of the septum primum continues and it loses its attachment to the roof of the atrium – thus it becomes the valve of the foramen ovale and this will persist until birth 2"
"4 atrioventricular endocardial cushions exist: two lateral, an anterior and a posterior – these encircle the atrioventricular canal"
"during week 5 endocardial cushions also appear in the truncus arteriosus – these form the truncal septum"
"endocardial cushions also develop in the walls of the conus cordis and form a conal septum that divides the conus into an anterolateral and posteromedial portion – these will become the smooth-walled right and left ventricular outflow tracts respectively"
"As the left atrium grows, these veins will ultimately be incorporated into it as the smooth left atrium"
"septum primum grows down towards these cushions – the space between these structures is the ostium primum and allows inter-atrial communication"
Expected headings
"Early development (week 3)"
"Further development of the heart chambers (weeks 4-6)"
"Atrial growth"
"Atrial septation"
"Atrioventricular canals"
"Great vessel formation"
"Ventricular septum formation"