From the Springer article: Cardiovascular Embryology
http://www.springerlink.com/openurl.asp?id=doi:10.1007%2fs00246-003-0585-1
by: Abdulla, R.; Blew, G. A.; Holterman, M. J.;
The atrial septum is initially formed by the septum primum which grows towards the fused middle portion of the atrio-ventricular endocardial cushions. A fenestration appears within the septum primum, just before it completes its growth. A second septum, just right to the septum primum grows and covers the fenestration, but continue to allow communication between the two atria (patent foramen ovale).
Journal: Pediatric Cardiology Vol. 25 Issue 3
DOI: 10.1007/s00246-003-0585-1
Published: 2004-06-01
5. Septum secundum contains a permanent opening (foramen ovale)
6. Foramen secundum enlarges and upper part of septum primum degenerates.
7. Remaining portions of septum primum forms valve of foramen ovale.
KerwinKoodie 1 year ago