ostium primum การใช้

As the septum primum grows, the ostium primum progressively narrows.
The ostium secundum provides communication between the atria after the ostium primum closes completely.
Before the ostium primum is completely occluded, a second opening called the ostium secundum begins to form in the septum primum.
The crescent shape prevents the complete closure of the atria allowing blood to be shunted from the right to the left atrium through the opening known as the ostium primum.