2008 Volume 40 Issue 2 Pages 58-66
In chicken embryos and chickens two and markedly long ductus arteriosus were detected. They connected left or right pulmonary artery with aorta and were divided into proximal and distal parts. Histologically the proximal part showed the structure of muscular artery and the distal one that of elastic artery. The lumen of the proximal part became obliterated by formation of the intimal cushion on the third day after hatching and thereafter the replacement of mascular elements by connective tissue occurred gradually in the ductal wall. The lumen of distal part was occluded within 60 days after hatching.