Pathways of intestinal lymph drainage in normal sheep and in sheep following thoracic duct occlusion

Abstract The pathways by which intestinal lymph enters the blood were studied with radiologic and radioactive tracer techniques in normal sheep and in sheep after thoracic duct occlusion. It was concluded that direct connections between the intestinal lymphatics and blood vessels in the abdomen and caudal thorax in normal sheep are very uncommon if they occur at all. During the first few days after the thoracic duct of sheep was occluded in the thorax, transfer of protein from intestinal lymph to blood was slow. At this time, the abdominal lymphatics were grossly dilated and lymphatic valves incompetent. After about 1–2 weeks, the abdominal lymphatics were of more normal size and drainage of lymph protein to the blood occurred more rapidly. At least some of this protein entered the blood within lymph nodes. After 4–7 weeks, direct vascular connections between the thoracic duct and hemiazygos vein had developed.