Anatomical closure of the ductus arteriosus: a study in 35 specimens

The process of anatomical ductal obliteration appears to be gradual and to involve proliferation of intima and media (mainly the latter) producing mounds, mucoid-filled spaces and fragmentation of the internal elastic membrane. Dissociation of the inner media may also be involved. The persistent ductus can be recognized histologically, and its clinical significance is discussed.