Compartmentalized ocular lymphatic system mediates eye-brain immunity.

The eye, an anatomical extension of the central nervous system (CNS), exhibits many molecular and cellular parallels to the brain. Emerging research demonstrates that changes in the brain are often reflected in the eye, particularly in the retina1. Still, the possibility of an immunological nexus between the posterior eye and the rest of the CNS tissues remains unexplored. Here, studying immune responses to herpes simplex virus in the brain, we observed that intravitreal immunization protects mice against intracranial viral challenge. This protection extended to bacteria and even tumours, allowing therapeutic immune responses against glioblastoma through intravitreal immunization. We further show that the anterior and posterior compartments of the eye have distinct lymphatic drainage systems, with the latter draining to the deep cervical lymph nodes through lymphatic vasculature in the optic nerve sheath. This posterior lymphatic drainage, like that of meningeal lymphatics, could be modulated by the lymphatic stimulator VEGFC. Conversely, we show that inhibition of lymphatic signalling on the optic nerve could overcome a major limitation in gene therapy by diminishing the immune response to adeno-associated virus and ensuring continued efficacy after multiple doses. These results reveal a shared lymphatic circuit able to mount a unified immune response between the posterior eye and the brain, highlighting an understudied immunological feature of the eye and opening up the potential for new therapeutic strategies in ocular and CNS diseases.

Anatomy and pathology of lymphatic vessels under physiological and inflammatory conditions in the mouse diaphragm.

The lymphatic vessels in the parietal pleura drain fluids. Impaired drainage function and excessive fluid entry in the pleural cavity accumulate effusion. The rat diaphragmatic lymphatics drain fluids from the pleura to the muscle layer. Lymphatic subtypes are characterized by the major distribution of discontinuous button-like endothelial junctions (buttons) in initial lymphatics and continuous zipper-like junctions (zippers) in the collecting lymphatics. Inflammation replaced buttons with zippers in tracheal lymphatics. In the mouse diaphragm, the structural relationship between the lymphatics and blood vessels, the presence of lymphatics in the muscle layer, and the distributions of initial and collecting lymphatics are unclear. Moreover, the endothelial junctional alterations and effects of vascular endothelial growth factor receptor (VEGFR) inhibition under pleural inflammation are unclear. We subjected the whole-mount mouse diaphragms to immunohistochemistry. The lymphatics and blood vessels were distributed in different layers of the pleural membrane. Major lymphatic subtypes were initial lymphatics in the pleura and collecting lymphatics in the muscle layer. Chronic pleural inflammation disorganized the stratified layers of the lymphatics and blood vessels and replaced buttons with zippers in the pleural lymphatics, which impaired drainage function. VEGFR inhibition under inflammation maintained the vascular structures and drainage function. In addition, VEGFR inhibition maintained the lymphatic endothelial junctions and reduced the blood vessel permeability under inflammation. These findings may provide new targets for managing pleural effusions caused by inflammation, such as pleuritis and empyema, which are common pneumonia comorbidities.

The lymphatic system of the uterine cervix: towards a more precise definition of the drainage routes.

PURPOSE: Lymph node involvement in cancer of the uterine cervix is a major independent prognostic factor for overall survival. The aim of our study was to examine the lymphatic drainage regions of the different parts of the uterine cervix. METHODS: An anatomical study of fresh cadavers was conducted by injecting patent blue in the anterior or posterior lip of the uterine cervix and dissecting drainage regions. Furthermore, a retrospective radiological and pathological studies were conducted on patients who were treated for early-stage cancer of the uterine cervix with lymph node involvement. Radiological analysis of pre-therapeutic MRIs and/or pathological analysis of surgical specimens showed the precise location of the tumour. A correlation between the anatomy of the primary lesion site and the lymphatic area involved was established. RESULTS: We administered 15 cadaveric injections: 8 in the anterior lip of the uterine cervix and 7 in the posterior one. For 100% of the anterior lip injections, lymphatic drainage was bilateral ileo-obturator (n = 8/8) combined with bilateral parametrial drainage. For the posterior injections, there was never any ileo-obturator drainage, and 6 of the 7 (75%) posterior injections drained in the posterior uterine serosa. Concerning the clinical study, we included 21 patients. We observed a non-significant tendency towards bilateral lymph node involvement when the tumour of the anterior lip. CONCLUSION: Physiological lymphatic drainage of the uterine cervix presents anatomical specificities, depending on the structure studied, anterior or posterior lip of the cervix. Better knowledge of these specificities should allow personalized surgery for each patient.

The underestimated posterior lymphatic drainage of the prostate: An historical overview and preliminary anatomical study on cadaver.

BACKGROUND: The evidence of pelvic lymph node metastases after radical prostatectomy (RP) with pelvic lymph node dissection (PLND) is one of the strongest prognostic factors for poor oncologic outcome. The extent of PLND, although representing a crucial step in RP, is still controversial. Currently, there is a critical drawback in clinical practice due to the lack of congruence between the known lymphatic drainage and cancer dissemination despite defined management by a surgical approach. We hypothesized the existence of alternative pathways for the lymphatic drainage of the prostate currently not considered in clinical daily practice. METHODS: We carried out a literature review of the anatomic description of nodal drainage of prostate reported by online databases (MEDLINE/PubMed, EBSCO, Web of Science, Ovid, and Scopus) and the original texts since the 18th century, with an additional anatomical dissection on a human cadaver to confirm theoretical data. RESULTS: The anatomical dissection study converged with the historical anatomical treatises in describing three groups of lymphatics devoted to carrying out prostatic nodal drainage. Apart from the ascending ducts from the cranial gland leading to the external iliac nodes; the lateral ducts leading to the hypogastric nodes; small lymphatic vessels from the posterior surface of the prostate, directed to the pararectal lymphatic plexus, in the direction of the lateral sacral lymph nodes and those at the sacral promontory (ie, pararectal and presacral lymph nodes) were observed. CONCLUSIONS: Our preliminary findings demonstrate that lymphatic drainage of the prostate extends beyond standard nodal templates actually considered in surgical daily practice, despite the knowledge reported by historical anatomical treatises. Further anatomical and experimental evidence are needed to investigate anatomical variability in humans, as well as to add more topographical details.

Organ-specific lymphatics play distinct roles in regulating HDL trafficking and composition.

Recently, peripheral lymphatic vessels were found to transport high-density lipoprotein (HDL) from interstitial tissues to the blood circulation during reverse cholesterol transport. This function is thought to be critical to the clearance of cholesterol from atherosclerotic plaques. The role of organ-specific lymphatics in modulating HDL transport and composition is, however, incompletely understood. This study aimed to 1) determine the contribution of the lymphatics draining the intestine and liver (which are major sites of HDL synthesis) to total (thoracic) lymph HDL transport and 2) verify whether the HDLs in lymph are derived from specific organs and are modified during trafficking in lymph. The mesenteric, hepatic, or thoracic lymph duct was cannulated in nonfasted Sprague-Dawley rats, and lymph was collected over 5 h under anesthesia. Whole lymph and specific lymph lipoproteins (isolated by ultracentrifugation) were analyzed for protein and lipid composition. The majority of thoracic lymph fluid, protein, and lipid mass was sourced from the mesenteric, and to a lesser extent, hepatic lymph. Mesenteric and thoracic lymph were both rich in chylomicrons and very low-density lipoprotein, whereas hepatic lymph and plasma were HDL-rich. The protein and lipid mass in thoracic lymph HDL was mostly sourced from mesenteric lymph, whereas the cholesterol mass was equally sourced from mesenteric and hepatic lymph. HDLs were compositionally distinct across the lymph sources and plasma. The composition of HDL also appeared to be modified during passage from the mesenteric and hepatic to the thoracic lymph duct. Overall, this study demonstrates that the lipoproteins in lymph are organ specific in composition, and the intestine and liver appear to be the main source of HDL in the lymph.NEW & NOTEWORTHY High-density lipoprotein in lymph are organ-specific in composition and derive mostly from the intestine and liver. High-density lipoprotein also appears to be remodeled during transport through the lymphatics. These findings have implications to cardiometabolic diseases that involve perturbations in lipoprotein distribution and metabolism.

Anatomy of the lymphovenous valve of the thoracic duct in humans.

The majority of lymph generated in the body is returned to the blood circulation via the lymphovenous junction (LVJ) of the thoracic duct (TD). A lymphovenous valve (LVV) is thought to guard this junction by regulating the flow of lymph to the veins and preventing blood from entering the lymphatic system. Despite these important functions, the morphology and mechanism of this valve remains unclear. The aim of this study was to investigate the anatomy of the LVV of the TD. To do this, the TD and the great veins of the left side of the neck were harvested from 16 human cadavers. The LVJs from 12 cadavers were successfully identified and examined macroscopically, microscopically, and using microcomputed tomography. In many specimens, the TD branched before entering the veins. Thus, from 12 cadavers, 21 LVJs were examined. Valves were present at 71% of LVJs (15/21) and were absent in the remainder. The LVV, when present, was typically a bicuspid semilunar valve, although the relative size and position of its cusps were variable. Microscopically, the valve cusps comprised luminal extensions of endothelium with a thin core of collagenous extracellular matrix. This study clearly demonstrated the morphology of the human LVV. This valve may prevent blood from entering the lymphatic system, but its variability and frequent absence calls into question its utility. Further structural and functional studies are required to better define the role of the LVV in health and disease.

Surgical Approach to Lymphedema Reduction.

PURPOSE OF REVIEW: For patients who have or may develop lymphedema due to oncologic resection, surgical options are available to prevent and treat this chronic disease. Here, we review the current pathophysiology, classification systems, surgical preventive techniques, and treatment options for lymphedema reduction. RECENT FINDINGS: Preventive surgical techniques, including de-escalation of axillary surgery, sentinel lymph node biopsy (SLNB), axillary reverse mapping (ARM), and lymphedema microsurgical preventive healing approach (LYMPHA), have been shown to reduce the incidence of lymphedema. Water displacement remains the gold standard for measuring limb volume and classification of lymphedema; however, lymphoscintigraphy and ICG lymphography are two novel imaging techniques that are now utilized to characterize lymphedema and guide management. Complete decongestive therapy (CDT) remains the mainstay of treatment. Vascularized lymph node transfer (VLNT) and lymphovenous bypass have shown promising results, particularly in advanced lymphedema stages. Combination therapy, incorporating both surgical and non-surgical approaches to lymphedema, yields best patient outcomes. Lymphedema is a chronic disease wherein management requires a combination of surgical and conservative treatments. Standardization in lymphedema staging, key outcome indicators, and quantitative data will be critical to establish the absolute best practices in lymphedema diagnosis and treatment.

Pelvic sentinel lymph node biopsy in endometrial cancer-a simplified algorithm based on histology and lymphatic anatomy.

OBJECTIVE: To achieve the full potential of sentinel lymph node (SLN) detection in endometrial cancer, both presumed low- and high-risk groups should be included. Perioperative resource use and complications should be minimized. Knowledge on distribution and common anatomical sites for metastatic SLNs may contribute to optimizing the concept while maintaining sensitivity. Proceeding from previous studies, simplified algorithms based on histology and lymphatic anatomy are proposed. METHODS: Data on mapping rates and locations of pelvic SLNs (metastatic and non-metastatic) from two previous prospective SLN studies in women with endometrial cancer were retrieved. Cervically injected indocyanine green was used as a tracer and an ipsilateral re-injection was performed in case of non-display of the upper and/or lower paracervical pathways. A systematic surgical algorithm was followed with clearly defined SLNs depicted on an anatomical chart. In high-risk endometrial cancer patients, removal of SLNs was followed by a pelvic and para-aortic lymphadenectomy. RESULTS: 423 study records were analyzed. The bilateral mapping rates of the upper and lower paracervical pathways were 88.9% and 39.7%, respectively. 72% of all SLNs were typically positioned along the upper paracervical pathway (interiliac and/or proximal obturator fossa) and 71 of 75 (94.6%) of pelvic node positive women had at least one metastatic SLN at either of these positions. Women with grade 1-2 endometroid cancers (n=275) had no isolated metastases along the lower paracervical pathway compared with two women with high-risk histologies (n=148). CONCLUSION: SLNs along the upper paracervical pathway should be identified in all endometrial cancer histological subtypes; removal of nodes at defined typical positions along the upper paracervical pathway may replace a site-specific lymphadenectomy in case of non-mapping despite tracer re-injection. Detection of SLNs along the lower paracervical pathway can be restricted to high-risk histologies and a full pre-sacral lymphadenectomy should be performed in case of non-display.

Long-Distance Tracing of the Lymphatic System with a Computed Tomography/Fluorescence Dual-Modality Nanoprobe for Surveying Tumor Lymphatic Metastasis.

Noninvasive visualization of deep tissue lymphatic metastasis is crucial for diagnosing malignant tumors and predicting prognosis. However, the limited diffusivity and specificity of imaging contrast agents that are transported in lymph vessels (LVs), even for those agents delivered by nanocarriers, make long-distance tracing of the lymphatic system in vivo challenging. Here, we develop a computed tomography (CT)/fluorescence dual-modality phospholipid nanoprobe (PL(I/D)NP) with a negative charge and sub-60 nm size. By using micro-CT, we noninvasively traced the LVs from the subcutaneous injection site in feet to the thoracic ducts with an entire length of ∼68 mm and measured the volume of the lymph nodes (LNs) and their separation distance along the LVs. For diagnostic imaging of tumor lymphatic metastasis, all LNs with metastasis were identified in vivo. Thus, with their long-distance diffusivity, high lymphatic capillary specificity, and quantifiability, the PL(I/D)NPs combined with noninvasive imaging accurately depicted the changes in the lymphatic system under pathologic conditions, especially cancer metastasis, which indicates their high potential for clinical applicability.

The discovery of the lymphatic system in the seventeenth century. Part V: an ode to the nerves.

The English anatomists Francis Glisson and Thomas Wharton introduced theories on the use of recently discovered lymphatic system in the1650s. Their main idea was that membranous tissues were supplied by nerves with a vital fluid produced within nutritive glands, to be carried to the brain and thence from the brain to all membranous tissues, including glands. They stated that the distribution of the vital fluid was based on the similarity between its ingredients and the needs of the recipient tissues, and not on the weight, size or location of pores encountered, as maintained by Descartes. Lymph, a mixture of waste from the consumed vital fluid and moisture transuded by arterial capillaries, was absorbed by the lymphatic vessels to be excreted via excretory glands, or to be diverted to the venous system by reductive glands. The theories of Glisson and Wharton were very soon rejected to be replaced by a mechanistic philosophy, a legacy of Descartes' theories.

Anatomical study of the left superior mediastinal lymphatics for tracheal branches of left recurrent laryngeal nerve-preserving mediastinoscope-assisted surgery in esophageal cancer.

PURPOSE: Curative treatment of esophageal cancer requires meticulous superior mediastinal lymphadenectomy, in addition to esophagectomy, because superior mediastinal lymph node metastases are common in esophageal cancer. When preserving the tracheal branches of the left recurrent laryngeal nerve (RLN), good anatomical understanding is required for confirmation of the positional relationships between the courses of lymphatic vessels, lymph node distribution, and the left RLN and its tracheal branches. We performed a detailed anatomical examination of these relationships. METHODS: Macroscopic anatomical observation and histological examination was performed on cadavers. In addition to hematoxylin and eosin staining, immunostaining using antipodoplanin antibody D2-40 (podoplanin) was performed to identify the lymphatic vessels. RESULTS: The tracheal branches of the left RLN were clearly observed, but no lymphatic vessels crossing the ventral or dorsal side of the branches were identified either macro-anatomically or histologically. CONCLUSION: No complex lymphatic network structure straddling the plane composed of tracheal branches of the left RLN was found in the left superior mediastinum. This suggests that dissection of the lymph nodes around the left RLN via the pneumomediastinum method using the left cervical approach may allow preservation of the tracheal branches of the left RLN by maintaining dissection accuracy.

Anatomy of the cutaneous lymphatic system of the trunk: a clinico-anatomical study of 90 cutaneous melanomas.

PURPOSE: The cutaneous lymphatic system of the trunk is a complex network, the anatomical knowledge of which remains unclear. The lymphatic system plays a major role in the dissemination of lymphophilic cancers like melanomas. The aim of this study was to improve our knowledge, optimize the care of patients with cutaneous tumors of the trunk, and to use our clinical experience of the topography of pathologic lymph nodes related to cutaneous melanomas and depicted by lymphoscintigraphy. MATERIALS AND METHODS: This prospective study included 90 consecutive patients who had primary resection of cutaneous melanoma of the trunk between June 2011 and January 2015. All patients had lymphatic mapping by lymphoscintigraphy, followed by sentinel lymph node procedure. We compared data of lymphatic imaging (lymphoscintigraphy and SPECT-CT) and surgery. We divided the trunk into 36 regions based on cutaneous anatomical landmarks to determine the topography of the lymphatic system for each tumor. RESULTS: Our study showed cutaneous lymphatic drainage of melanomas of the trunk in 16 different areas. This drainage could be single or multiple. We observed that drainage could be controlateral in medial regions of the trunk, and lymphatic pathway could be retrograde. This drainage could be bilateral for medial regions and mainly into axillary areas for regions above L1 level. Posterior regions of the trunk had more diversity of drainage areas than anterior regions. CONCLUSIONS: Cutaneous lymphatic drainage of the trunk was not limited to axillary and inguinal areas, showed interindividual variability, and was single or multiple, unilateral or bilateral, and unpredictable.

Three-dimensional computer-assisted dissection of pancreatic lymphatic anatomy on human fetuses: a step toward automatic image alignment.

PURPOSE: Pancreatic cancer is the fourth cause of death by cancer worldwide. Lymph node (LN) involvement is known to be the main prognostic factor. However, lymphatic anatomy is complex and only partially characterized. The aim of the study was to study the pancreatic lymphatic system using computer-assisted anatomic dissection (CAAD) technique and also to update CAAD technique by automatizing slice alignment. METHODS: We dissected three human fetuses aged from 18 to 34 WA. 5-µm serial sections of duodeno-pancreas and spleen blocks were stained (hematoxylin-eosin, hematoxylin of Mayer and Masson trichrome), scanned, aligned and modeled in three dimensions. RESULTS: We observed a rich, diffuse but not systematized lymphatic network in the peri-pancreatic region. There was an equal distribution of LNs between the cephalic and body-tail portions. The lymphatic vascularization appeared in continuity from the celiac trunk to the distal ends of its hepatic and splenic arterial branches parallel to the nerve ramifications of the celiac plexus. We also observed a continuity between the drainage of the pancreatic head and the para-aortic region posteriorly. CONCLUSION: In view of the wealth of peri-pancreatic LNs, the number of LNs to harvest could be increased to improve nodal staging and prognostic evaluation. Pancreatic anatomy as described does not seem to be compatible with the sentinel LN procedure in pancreatic surgery. Finally, we are now able to offer an alternative to manual alignment with a semi-automated alignment.

[Lymphatic system of the eye]. / Limfaticheskaia sistema glaza.

Existence of lymphatic outflow of intraocular fluid is still an open question. Identification of the lymphatic capillaries and vessels in various human organs in normal and pathological conditions became possible with discovery of endotheliocyte markers for lymphatic vessels. However, the available information on the presence of lymphatic structures in the human eye is inconsistent and uncertain. The data on lymphatic drainage of the eye is of interest, particularly because it may help understand glaucoma pathogenesis, mechanisms of development of eye inflammatory diseases, and develop pathogenetic therapies. The article reviews literature and presents the authors' own views on lymphatic drainage of the human eye.

Scholars and scientists in the history of the lymphatic system.

The discovery of the lymphatic system has a long and fascinating history. The interest in anatomy and physiology of this system paralleled that of the blood cardiocirculatory system and has been maybe obscured by the latter. Paradoxically, if the closed blood system appeared open in Galen's anatomy and physiology, and took a very long time to be correctly described in terms of pulmonary and general circulation by ibn Al-Nafis/Michael Servetus/Realdo Colombo and William Harvey, respectively, the open lymphatic system was incorrectly described as a closed circuit connected with arteries and veins. In ancient times only macroscopic components of the lymphatic system have been described, although misinterpreted, including lymph nodes and lacteals, the latter being easily identified because of their milk-like content. For about 15 centuries the dogmatic acceptance of Galen's notions did not allow a significant progress in medicine. After Vesalius' revolution in anatomical studies, new knowledge was accumulated, and the 17th century was the golden age for the investigation of the lymphatic system with several discoveries: gut lacteals (Gaspare Aselli), cloacal bursa (Hieronimus Fabricius of Acquapendente), reservoir of the chyle (Jean Pecquet), extra-intestinal lymphatic vessels (Thomas Bartholin and Olaus Rudbeck dispute), hepatic lymph circulation (Francis Glisson). In the Enlightenment century Frederik Ruysch described the function of lymphatic valves, and Paolo Mascagni provided a magnificent iconography of the lymphatic network in humans. In recent times, Leonetto Comparini realized three-dimensional reconstructions of the liver lymphatic vessels, and Kari Alitalo discovered the lymphatic growth factor/receptor system. Far from a complete understanding of its anatomy and function, the lymphatic system still needs to be profoundly examined.

Lymphosome concept: Anatomical study of the lymphatic system.

The gross anatomical study of the lymphatic system in humans and animals has been suspended for almost 100 years. This article introduces the author's technique for investigating the lymphatic system using the concept of the lymphosome. In revisiting the anatomical study of the lymphatic system, our updated knowledge can potentially be utilized either to reassure surgeons about their current procedures in the surgical management of cancers and lymphedema or assist them to refine them. J. Surg. Oncol. 2017;115:13-17. © 2016 Wiley Periodicals, Inc.

Perirenal lymphatic systems: Evaluation using spectral presaturation with inversion recovery T2 -weighted MR images with 3D volume isotropic turbo spin-echo acquisition at 3.0T.

PURPOSE: To evaluate the normal anatomy of the perirenal lymphatics using spectral presaturation with inversion recovery (SPIR) T2 -weighted magnetic resonance imaging (MRI) with 3D volume isotropic turbo spin-echo acquisition (VISTA) at 3.0T. MATERIALS AND METHODS: This retrospective study was approved by the two Institutional Review Boards and informed consent was waived. Thin-collimated axial images obtained using SPIR T2 -weighted MR imaging sequences with 3D VISTA at 3.0T from 50 patients (100 kidneys) with normal renal function were retrospectively reviewed. The perirenal lymphatic vessels were defined as fluid signal intensity structures on this MRI sequence. Two readers independently assessed the degree of visualization of the perirenal lymphatics using a 4-point scale in four anatomical regions, including the renal hilar, capsular, communicating pericapsular, and subfascial lymphatics, and interobserver agreement was evaluated with weighted kappa statics. The detectability of each lymphatic system was calculated for each reader using confidence level ratings of grades 1 and 2 as positive and grades 3 and 4 as negative. RESULTS: Interobserver agreement for the visualization grades was almost perfect (kappa value = 0.9). The renal hilar lymphatics along the renal vein were clearly identified in all patients. The detectability of other perirenal lymphatics was 44% for the capsular lymphatics, 39% for communicating pericapsular lymphatics, and 22% for the subfascial lymphatics. There was no laterality regarding the detectability of the perirenal lymphatics. CONCLUSION: The findings of this study support the feasibility of SPIR T2 -weighted MR images with 3D-VISTA at 3.0T for evaluating the perirenal lymphatic systems. J. MAGN. RESON. IMAGING 2016;44:897-905.

A comprehensive review of the natural lymphaticovenous communications and their role in lymphedema surgery.

Cancer-related lymphedema is a progressive, chronic condition that impairs quality of life. Its pathophysiology and the mechanisms of action of current reconstructive surgical treatments are not fully understood but lymphaticovenous communications may play a key role. We review the available literature on lymphaticovenous communications and their implications in lymphedema surgery, and propose a subclassification of lymphaticovenous communications. J. Surg. Oncol. 2016;113:374-380. © 2016 Wiley Periodicals, Inc.

X-ray-induced shortwave infrared biomedical imaging using rare-earth nanoprobes.

Shortwave infrared (SWIR or NIR-II) light provides significant advantages for imaging biological structures due to reduced autofluorescence and photon scattering. Here, we report on the development of rare-earth nanoprobes that exhibit SWIR luminescence following X-ray irradiation. We demonstrate the ability of X-ray-induced SWIR luminescence (X-IR) to monitor biodistribution and map lymphatic drainage. Our results indicate X-IR imaging is a promising new modality for preclinical applications and has potential for dual-modality molecular disease imaging.

Lymphedema: A General Outline of Its Anatomical Base.

The anatomic research of the lymphatic system has been a very controversial subject throughout due to the complexity of the methods for its visualization. More than 30 years ago, together with Prof. Caplan, we began the vascular anatomy research, focusing on the lymphatic anatomy, developing and adapting different techniques of injection. On the third Normal Anatomy Chair of Buenos Aires University, we summarized the lymphatic drainage of the breast and the limbs to interpret the anatomic bases of lymphedema.