Morphological and histological analysis of the thoracic duct at the jugulo-subclavian junction in Japanese cadavers.

The macroscopic arrangement of the termination of the thoracic duct (TD) was examined in detail in Japanese cadavers, and the distribution of various types of collagen, tenascin, laminin, and fibronectin in the framework of the wall of the thoracic duct termination was demonstrated. We identified several branching patterns and pathways of the TD (i.e., those terminating 1) at the venous angle (Type A); 2) at the end of the internal jugular vein (Type B); 3) at the the external jugular vein (Type C); or 4) in a complex with various branches (Type D). The TD often divided into two or three trunks before or after passing beneath the left brachiocephalic vein. Compared with the main trunk of the TD, fewer muscle fibers, elastic fibers, specific compounds of the extracellular matrices, and valvular connective tissues were found near the termination of the TD and the valves of the TD and veins. Smooth muscle cells were arranged irregularly in each region of the TD.