Patent formen ovale is due to failure of fusion of-

Cessation of placental blood flow and the beginning of respiration leads to changes in the vascular system at bihStructure/Vessel Remnant (In Adults) Timing of Closure Ductus aeriosus Ligamentum aeriosumQ Almost immediately after bih, by bradykirdn (released during inital inflation of lung) mediated contraction of muscular wall. Actual obliteration takes 1-3monthsUmbilical aeries - Distal pa form medial umbilical ligaments - Proximal poion remains open as superior vesical aeriesFew minutes after bih (d/t thermal, mechanical & 02 tension change), athough actual fibrous obliteration may take 2-3 monthsUmbilical vein (left) Ductus venosus Ligamentum teres hepatis Ligament venosum Occurs sholy after that of umbilical aeriesSeptum prinum Septum secundum (lower free edge)Fossa ovalis Annulus ova us The first breath causes increased left atrial pressure pressing the septum primum against septum secundum Vt closure of ovalforamen. During 1st day its reversible and complete fusion takes about 1 year