The endocardial cushion serves as a makeshift valve until then.

It showed that there was insufficient formation of the endocardial cushion.

At the end of the fourth week, two atrio-ventricular endocardial cushions appear.

Endocardial cushion defect occurs while a baby is still growing in the womb.

The parts of the heart described above are formed from an embryonic structure called the endocardial cushions.

The structures that develop from the fusion of the endocardial cushions are:

Endocardial cushion defects are the most common congenital heart defect that is associated with Down's syndrome.

Tissue masses called endocardial cushions develop into atrioventricular and conotroncal regions.

In the fifth week, the posterior end terminates in the center part of the upper endocardial cushion.

The IV septum grows upward towards the endocardial cushion.

A problem in endocardial cushion development or remodeling is thought to be associated with atrioventricular septal defect.

The two ends of the septum extend into the interior of the endocardial cushion in the atrioventricular canal.

An atrioventricular septal defect also known as endocardial cushion defect is the most common form with up to 40% of patients affected.

An intra-muscular ventricular septum begins to grow from the common ventricle to the atrio-ventricular endocardial cushions.

Notch signaling is involved early in the formation of the endocardial cushions and continues to be active as the develop into the septa and valves.

The endocardial cushions are two areas of thickening that eventually develop into the wall (septum) that separates the four chambers of the heart.

Right before the septum primum fuses with the endocardial cushions there's a temporary space called the foramen primum.

Incomplete formation of the endocardial cushions can lead to atrioventricular septal defects, such as an ostium primum defect.

The septum primum eventually fuses with the endocardial cushion, closing the ostium primum off completely.

Foxp1 regulates cardiac outflow tract, endocardial cushion morphogenesis and myocyte proliferation and maturation.

From the roof of the primitive atrium descends the septum primum, which grows towards the endocardial cushions within the atrial canal.

The opening between the bottom edge of the spetum primum and endocardial cushions are the ostium primum (first opening).

Endocardial cushion defects are associated with abnormalities of the atrioventricular valves (the mitral valve and the tricuspid valve).

These thickenings or endocardial cushions will go on to fuse and remodel to eventually form the valves and septa of the mature adult heart.

The increasingly smaller gap below it (before it fuses with the endocardial cushion) is known as the ostium primum (i.e. "the first opening").