FETAL IN-SITU CARDIOVASCULAR AND PULMONARY MORPHOLOGY OF VASCULAR RING DUE TO LEFT AORTIC-ARCH AND RIGHT DUCTUS-ARTERIOSUS IN RATS

We studied 17 fetal rats with vascular ring composed of the left aorti c arch and right ductus arteriosus and 7 fetal rats with the mirror-im age arrangement. The vascular ring of this type was induced by adminis tration of bis-diamine (200 mg) on the 9th and 10th day of pregnancy i n rats. In the most severe case, the esophagus and trachea were compre ssed completely and no inner space was left, and localized and diffuse tracheal stenosis was prominent. The fetal lung mass was increased as the stenosis of the ring was severe. The thoracic descending aorta wa s positioned in the left side, and was contrasted with the clinically observed right descending aorta in this postnatal anomaly. Thus we are reporting two new findings in the fetal vascular ring with the left a ortic arch and the right ductus arteriosus: increased lung mass and le ft descending aorta in a fetal animal model.