<prompt> Anatomical closure of ductus aeriosus occurs at?Bih3-4 day10 day30 day  <response>: D i.e. 30 days The ductus aeriosus constricts at bihQ, but there is often a small shunt of blood from the aoa to left pulmonary aery for 24- 48 hours in normal healthy, full term infant. At the end of 24 hours, 20 of ducts are functionally closed, 82 by 48 hours, and 100 at 96 hours 4 days2In premature infants and in those with persistent hypoxia, DA may remain open much longer. 02 P02 50 mmHg is the most impoant factor in controlling closure of DA in fullterm infants. The DA of premature infants is less responsive to Closure is mediated by bradykinin released during initial inflation of lungComplete anatomical obliteration by proliferation of the intima may take 1-3 monthsQ and is probably mediated by transforming growth factor TGF-0During felat life the patency of the ductus aeriosus DA is mintained by low 02 content endogenously produced prosthglandins. So inhibitors of prostaglendin synthesis, such as indometluicin, can cause constriction of a patent ductus aeriosus in premature infants. 