Lymphatic drainage of heart and lungs: comparison between pig and man.

In its anatomy and physiology the pig is comparable with humans and its organs can be considered for xenotransplantation. We have studied the lymphatic drainage of the heart and lungs in 15 pigs. A coloured mass was injected into the myocardium and/or beneath the visceral pleura. The first nodes coloured were directly injected again. No lymph node was observed inside the heart and lungs. The first lymph nodes coloured were the peritracheobronchial nodes. There was no node in front of the thoracic trachea (Barety's compartment in man). Left suprabronchial nodes were connected with the thoracic duct in the mediastinum. The lymphatics of the heart and lungs in the pig are similar to those of human. Phylogenesis explains "skipping" metastases and the significance of N1 disease in lung cancer, as well as chylothorax occurring after heart and lung surgery.