Post-natal development of the arterial bronchial circulation in the dog (a morphometric study)

The postnatal development of the arterial bronchial circulation was studied by morphometric methods in the puppy. The internal diameter and the wall thickness of injected bronchial and pulmonary arteries was measured at different distances from the hilum and expressed as ratios that were studied at different ages. The lumen of the bronchial arteries dilate at proximal levels and the wall thickness decreases at distal levels these facts being due to the expansion of the bronchial circulation in the postnatal period. The role of the bronchial circulation in the development of the lung is discussed.