Extrapulmonary morphological findings of the bronchial artery in the rat

Although the rat is often adopted as the experimental model in investigations on the respiratory system, macroscopic findings of the bronchial arteries have not been described in detail satisfactorily. We dissected the extrapulmonary course of this artery from the origin to the pulmonary hilus in the rat. One right and one left bronchial arteries were observed. The right artery arose from the right highest intercostal artery, ran together with the right vagus nerve along the right side of the trachea and right principal bronchus, and reached the pulmonary hilus. The stem artery bifurcated into two main branches at the cranial border of the right principal bronchus. The left one arose from the left internal thoracic artery, ran along the left vagus nerve on the ventral surface of the thoracic aorta and reached the dorsal surface of the left principal bronchus. During their courses the right and left bronchial arteries gave off an ascending branch running along the course of the recurrent laryngeal nerve and several small branches to the trachea, esophagus, bronchus, and lymph nodes of the vicinity. The existence of species differences in the morphologic, pharmacologic, and physiologic characteristics of the bronchial arteries is implied by present and previous results as well as the need for caution in selecting laboratory animals if the results are to be applied to humans.