DOI: 10.36347/sjams.2022.v10i03.004

Pages: 286-290

Objective: To determine morphological and ultrastructural details of the collecting lymph vessel, lumbar trunk and thoracic duct of the rat. Methods: Sixteen adult SD rats were utilized for the study. A small amount of 6% hydrogen peroxide was applied to find the lymph vessel in the dorsodistal hind-limb and sides of the abdominal aorta in the rat. Under a surgical microscope, the vessel was injected by Indian ink or a radiopaque mixture via a fine needle to locate sites of the collecting lymphatic vessel, lumbar trunk and thoracic duct. Vessels were then harvested for the histological and transmission electron microscopic examinations. Results: Diameters of the collecting lymph vessel, lumbar trunk and thoracic duct in the rat were diverse, small in the former and large in the latter. Containing multiple valves in the lumen, their walls were very thin and composed of three layers of tissue. Ultrastructures of the tunica intima and externa of these vessels were similar. A single layer of endothelium cells with a discontinuous basement membrane formed the tunica intima of the vessel. One or two discontinuous layers of smooth muscle cells was found in the tunica media of the collecting lymph vessel, one to three layers of smooth muscle cells in the lumbar trunk and three to five layers of smooth muscle cells in the thoracic duct. The tunica externa of the vessel was comprised by connective tissue (collagen fibrils) and fibroblasts. Conclusion: Morphological and ultrastructural details of the collecting lymph vessel, lymphatic trunk and duct in the rat have been demonstrated that may help for the purpose of further lymphatic vessels studies.