ABSTRACT
Circulating prostaglandins maintain ductal patency during the fetal period. At birth an elevated arterial pOB2 Binhibits prostaglandin synthetase, resulting in ductal constriction. Permanent DA closure requires loss of cells from the muscular media and neointimal proliferation. The fibrosed DA becomes the ligamentum arteriosum. Functional closure of the DA occurs within a few hours of birth in term infants and is usually irreversible within 6 weeks.
