The detailed knowledge of the morphological structure, drainage pathways and patterns, the first tier lymph node of the cardiac lymphatic and its relationship with the circulatory system has not yet been completed. Although, the cardiac lymphatics had been described with renewed interest in past years, which was attributed to the transparent nature of lymphatic vessels that are difficult to be observed. In this study, cardiac lymphatics of the goat heart were perfused by a direct microinjecting technique with a radiopaque mixture. This demonstrated the subepicardial and subendocardial lymph capillary networks communicating with transmyocardial lymph vessels and then entering to subepicardial collecting lymph vessels that were directed toward the atrio-ventricular sulcus where they form a confluence from which the main cardiac lymph channels. We also found that: 1) the quantity and caliber of collecting lymph vessels varied in each goat heart; 2) drainage patterns of lymph vessels in the goat heart were different in individuals; 3) the first tier lymph node that each major lymph vessel drained to was different; and 4) multiple lymphatic-venous anastomosis sites have been confirmed to exist in the subepicardium of the left and right ventricles of each goat heart, which may be the morphological structure to accelerate the return of intercellular fluid to the venous system during excessive exercise of the heart. Therefore, the information may provide reference for further study in physiological and pathological conditions of the human heart.

Keywords: Goats, Heart, Lymphatic vessel, Lymph nodes, Lymphovenous anastomosis