Interior of dorsal half of heart from a human embryo of about thirty days. (Ostium primum visible below septum primum, but not labeled.)
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|Latin
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|colspan="2"|[subject #135 ]
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|System
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|Carnegie stage
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|Days
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|Precursor
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|Gives rise to
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|MeSH
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|Dorlands/Elsevier
|colspan="2"|[o_09/12602009]
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In the developing heart, for a time the atria communicate with each other by an opening, the ostium primum of Born (interatrial foramen primum), below the free margin of the septum.
This opening is closed by the union of the septum primum with the septum intermedium, and the communication between the atria is reëstablished through an opening which is developed in the upper part of the septum primum; this opening is known as the foramen ovale (ostium secundum of Born) and persists until birth.
