Lymphatic Territories (Lymphosomes) in the Rat: An Anatomical Study for Future Lymphatic Research

Abstract

Background Understanding the precise anatomy in experimental animals is crucial to correct design of research projects. Rats are commonly used for scientific research in plastic surgery because of their availability in academic institutions, moderate cost and sizable vessels for microsurgical procedures. In past publications about rat anatomy, lymphatic mapping has been limited and incomplete. The aim of this study was to comprehensively map the superficial lymphatic system in the rat. Methods Twenty-seven Sprague–Dawley rats were used for this study. Indocyanine green (ICG) fluorescence lymphography was used to identify the lymphatic vessels and lymph nodes. Under general anaesthesia, ICG was injected intradermally at multiple spots along the dorsal and medial midlines, front and hind paws, and tail. The course of the lymphatic vessels was traced on the skin with marker pen and photographed. The superficial lymphatic vessels in each rat were sketched on a graphic template and all the templates were superimposed using graphic software to define the relationship between the lymphatic vessel and sentinel node. Results ICG fluorescence lymphography was able to demonstrate the superficial lymphatic vessels in the rat. Six groups of regional lymph node/s were identified and lymphatic pathways to those nodes delineated. Our lymphosome concept was successfully applied to the rat, with six lymphosomes identified. Conclusions We succeeded in performing superficial lymphatic mapping in the rat. Our anatomical findings can provide further information about the lymphatic system in the normal state and promote understanding of pathological changes generated by surgical manipulation for future studies.

Molecular Weight-dependent Diffusion, Biodistribution, and Clearance Behavior of Tetra-armed Poly(ethylene glycol) Subcutaneously Injected into the Back of Mice

“…A portion of subcutaneously injected PEGs migrates into regional lymph nodes. Similar to reports for macromolecules, 26,28 the lymphatic vascular plays a significant role in the migration of subcutaneously injected PEGs into the blood circulatory system.…”

Molecular Weight-Dependent Diffusion, Biodistribution, and Clearance Behavior of Tetra-Armed Poly(ethylene glycol) Subcutaneously Injected into the Back of Mice

“…A portion of the subcutaneously injected PEGs migrates into regional lymph nodes. Similar to reports for macromolecules, 27 , 29 the lymphatic vascular plays a significant role in the migration of subcutaneously injected PEGs into the blood circulatory system.…”

“…A portion of the subcutaneously injected PEGs migrates into regional lymph nodes. Similar to reports for macromolecules, 27,29 the lymphatic vascular plays a significant role in the migration of subcutaneously injected PEGs into the blood circulatory system. It is well-known that circulating macromolecules such as PEG show a differential organ distribution depending on their M w .…”

Lymphovenous Anastomoses and Microscopic Lymphatic Ligations for the Treatment of Persistent Lymphocele

“… 20 According to the concept of lymphosomes, superficial lymphatic vessels diverge and merge on their way to the lymph node and do not cross each other in humans, demarking and dividing the skin into certain lymphatic territories, which are referred to as lymphosomes. 21 Preferential lymphatic drainage patterns seem to exist such that for a given tissue space, fluid drainage is the primary responsibility of one single vessel, whereas any additional vessels in the area serve as overflow or reserve transport routes for large fluid loads. 22 If these connections are not present and/or high-flow afferent lymphatic vessels are injured, LF might be promoted.…”