Vascular endothelial growth factor-D is a key molecule that enhances lymphatic metastasis of soft tissue sarcomas

Studies on lymph node metastasis of soft tissue sarcomas are insufficient because of its rarity. In this study, we examined the expressions of vascular endothelial growth factor (VEGF)-C and VEGF-D in soft tissue sarcomas metastasized to lymph nodes. In addition, the effects of the two molecules on the barrier function of a lymphatic endothelial cell monolayer against sarcoma cells were analyzed. We examined 7 patients who had soft tissue sarcomas with lymph node metastases and who had undergone neither chemotherapy nor radiotherapy before lymphadenectomy. Immunohistochemistry revealed that 2 of 7 sarcomas that metastasized to lymph nodes expressed VEGF-C both in primary and metastatic lesions. On the other hand, VEGF-D expression was detected in 4 of 7 primary and 7 of 7 metastatic lesions, respectively. Interestingly, 3 cases that showed no VEGF-D expression at primary sites expressed VEGF-D in metastatic lesions. Recombinant VEGF-C at 10(-8) and VEGF-D at 10(-7)and 10(-8)g/ml significantly increased the random motility of lymphatic endothelial cells compared with controls. VEGF-D significantly increased the migration of sarcoma cells through lymphatic endothelial monolayers. The fact that VEGF-D induced the migration of fibrosarcomas through the lymphatic endothelial monolayer is the probable reason for the strong relationship between VEGF-D expression and lymph node metastasis in soft tissue sarcomas. The important propensities of this molecule for the increase of lymph node metastases are not only lymphangiogenesis but also down-regulation of the barrier function of lymphatic endothelial monolayers, which facilitates sarcoma cells entering the lymphatic circulation.     

Prognostic Significance of Peritumoral Lymphatic Vessel Density and Vascular Endothelial Growth Factor Receptor 3 in Invasive Squamous Cell Cervical Cancer

Cervical cancer is known to metastasize primarily by the lymphatic system. Dissemination through lymphatic vessels represents an early step in regional tumor progression, and the presence of lymphatic metastasis is associated with a poor prognosis. In patients who have undergone a radical hysterectomy, lymphovascular space invasion (LVSI), assessed on hematoxylin and eosin-stained slides, is a major factor for adjuvant therapy in patients with cervical cancer. With the advent of a lymphatic endothelial cell-specific marker, such as D2-40, it is now possible to distinguish between blood and lymphatic space invasion (LSI). In this study, the utility of D2-40 was assessed for the detection of lymphatic vessel density (LVD) and identification of LSI. The expressions of vascular endothelial growth factor receptor-3 (VEGFR-3), VEGF-C, tyrosine receptor kinase-2, and angiopoietin-1 were assessed by immunohistochemical methods on 50 patients with squamous cell carcinoma of the cervix. Clinicopathologic characteristics, including pelvic lymph node metastasis, were correlated with the above histochemical findings. We found that lymphangiogenesis, measured by an increase in peritumoral LVD, was significantly associated with positive lymph node status (P < .005). VEGFR-3 expression was significantly associated with LVD (P < .05). D2-40 staining verified LSI (P = .03) and surpassed that of hematoxylin and eosin-identified LVSI (P = .54). In conclusion, lymphangiogenic markers, specifically LVD quantified by D2-40 and VEGFR-3, are independently associated with LSI and lymph node metastasis in patients with early squamous cell carcinoma of the cervix treated with radical hysterectomy and pelvic lymphadenectomy.     

Immune dynamics in the pathogenesis of human lymphatic filariasis

Despite the longstanding recognition of the spectral nature of human disease due to lymphatic filariasis, immunologists interested in pathogenesis have mostly examined patients classified as being at either one extreme pole or the other. While the clinically asymptomatic individuals with microfilaremia who sit at one pole always have active infection, it has been difficult to define who else on the clinical spectrum is actively infected with living adult worms. In this review, David Freedman discusses how the ability to measure circulating filarial antigen in patient serum has advanced our ability to understand the immunopathogenesis of lymphatic filariasis by improving the precision of patient classification. Recent work suggests that the presence (or absence) of antigenemia, rather than overt clinical manifestations of disease, is closely associated with specific cytokine responses. A framework for patient classification based on these findings is proposed.     

Abdominal lymphatic dysplasia and 22q11 microdeletion

We report the case of a child with 22q11 microdeletion who presented with abdominal lymphatic dysplasia resulting in exsudative enteropathy. This primitive and localized lymphatic malformation is consistent with the vascular theory in the velocardiofacial syndrome.     

Endothelin-mediated constriction of prenodal lymphatic vessels in the canine forelimb

Endothelin is a 21 amino acid peptide which is produced by the vascular endothelium and is believed to be the mediator of endothelium-dependent vasoconstriction. In the current study we assessed the ability of synthetic human endothelin-1 to affect prenodal lymphatic vessel contractility in the canine forelimb. Intralymphatic infusion of endothelin at 1.09 x 10(-9), 1.09 x 10(-8) and 1.09 x 10(-7) M significantly constricted lymphatic vessels as evidenced by dose-dependent increases in lymphatic perfusion pressure. The increase in lymphatic perfusion pressure seen during intralymphatic infusion of endothelin at 1.09 x 10(-8) M during the intra-arterial infusion of phentolamine was not significantly different from that seen prior to phentolamine, indicating that endothelin-mediated lymphatic constriction is not alpha-receptor mediated. Intra-arterial infusion of endothelin at three infusion rates significantly increased forelimb arterial, systemic and lymphatic perfusion pressures. The constriction seen when endothelin (1.09 x 10(-8) M) was infused intralymphatically in the intact lymphatic system was not significantly different from that observed when only the prenodal lymph vessel was perfused. This indicated that the lymph nodes and efferent lymph vessels do not contribute significantly to the lymphatic constriction produced by endothelin. These data are consistent with the hypothesis that endothelin may modulate lymphatic function under either normal or pathophysiological conditions.     

Breast cancer in patients with prior augmentation: presentation, stage, and lymphatic mapping

The purpose of this study was to determine whether breast cancer patients who had prior breast augmentation presented at a more advanced stage than nonaugmented breast cancer patients, and to determine the mode of presentation and effectiveness of lymphatic mapping and sentinel lymph node biopsy in this same group of patients. A total of 4186 breast cancer patients from 1987 to 2002 were reviewed. Patients who had augmentation before their diagnosis of breast cancer were compared with a control group of nonaugmented breast cancer patients. The Wilcoxon rank sum test was used to compare tumor size, node positivity, and stage. The patient's age at presentation was also compared by the two-sided pooled t test. Seventy-six patients who previously underwent augmentation were identified with 78 breast cancers. Seventy percent (48 of 69) were initially detected by palpation, whereas 30 percent (21 of 69) were initially identified mammographically. Fifty-three percent (n = 41) underwent mastectomy and 47 percent (n = 37) underwent a lumpectomy. This compares with a 63.6 percent (2615 of 4110) breast conservation rate in the nonaugmented population during the same time period. The two groups did not differ regarding (tumor) size (p = 0.77), nodal positivity (p = 0.32), or stage (p = 0.34). The mean time between implant placement and a diagnosis of breast cancer was 14 years. The average age of the patients who had previously undergone augmentation at breast cancer diagnosis was 49.5 years (SD, 9.0 years) versus 57.1 years (SD, 13.5 years) for the nonaugmented patients (p < 0.0001). Forty-nine of the patients underwent lymphatic mapping, with a 100 percent success rate in identifying the sentinel lymph node. There have been no clinically detected axillary recurrences in the patients who had a negative sentinel lymph node biopsy. Breast cancer patients who have undergone previous augmentation are more likely to present with a palpable mass. This initial mode of detection does not appear to translate into a larger tumor size or worse prognosis. Breast conservation and lymphatic mapping can be performed successfully in previously augmented patients.     

Receptor mechanisms of PAF mediated lymphatic constriction in the canine forelimb

Platelet activating factor (PAF) is a potent inflammatory lipid. In this study we assessed the ability of PAF to impact lymphatic vessel function by altering prenodal lymphatic resistance. Intralymphatic PAF (7.47 x 10(-6), 7.47 x 10(-5) and 7.47 x 10(-4) M) increased lymphatic perfusion pressure at the two highest infusion rates. PAF mediated lymphatic constriction was not altered by the intra-arterial infusion of phentolamine but was blocked by the intra-arterial infusion of the PAF receptor antagonist WEB 2170. These data indicate that in addition to PAF's effects on microvascular permeability, this agent may also impact the ability of the lymphatics to transport fluid through alterations in lymphatic smooth muscle tone. PAF mediated lymphatic constriction is not mediated by alpha-receptors but rather through PAF receptor mediated mechanism.     

Essential role of the coxsackie- and adenovirus receptor (CAR) in development of the lymphatic system in mice

The coxsackie- and adenovirus receptor (CAR) is a cell adhesion molecule predominantly associated with epithelial tight junctions in adult tissues. CAR is also expressed in cardiomyocytes and essential for heart development up to embryonic day 11.5, but not thereafter. CAR is not expressed in vascular endothelial cells but was recently detected in neonatal lymphatic vessels, suggesting that CAR could play a role in the development of the lymphatic system. To address this, we generated mice carrying a conditional deletion of the CAR gene (Cxadr) and knocked out CAR in the mouse embryo at different time points during post-cardiac development. Deletion of Cxadr from E12.5, but not from E13.5, resulted in subcutaneous edema, hemorrhage and embryonic death. Subcutaneous lymphatic vessels were dilated and structurally abnormal with gaps and holes present at lymphatic endothelial cell-cell junctions. Furthermore, lymphatic vessels were filled with erythrocytes showing a defect in the separation between the blood and lymphatic systems. Regionally, erythrocytes leaked out into the interstitium from leaky lymphatic vessels explaining the hemorrhage detected in CAR-deficient mouse embryos. The results show that CAR plays an essential role in development of the lymphatic vasculature in the mouse embryo by promoting appropriate formation of lymphatic endothelial cell-cell junctions.     

Modulation of lymphatic muscle contractility by the neuropeptide substance P

Substance P (SP) is a neuropeptide associated with sensory innervation of lymphoid tissue and a suspected modulator of lymphatic function in inflammation. Only a few studies have examined the effects of SP on lymphatic contraction, and it is not clear to what extent SP acts directly on the lymphatic muscle and/or endothelium or indirectly through changes in intraluminal filling pressure secondary to increases in capillary permeability/filtration. We tested the effects of SP on the spontaneous contractions of rat isolated mesenteric lymphatic vessels under isometric and isobaric conditions, hypothesizing that low concentrations would stimulate lymphatic pumping by enhancing lymphatic muscle contraction in a manner complementary to the effect of increased preload. Under isometric conditions, SP (10 nM) dramatically enhanced lymphatic chronotropy and inotropy. Unlike guinea pig lymphatics, SP actions were not blocked by cyclooxygenase or PLA(2) inhibition. In the absence of SP, ramp increases in isometric preload resulted in x approximately 1.6 increases in contraction amplitude (Amp) and x approximately 1.7 increases in frequency (Freq). SP increased Freq by x approximately 2.4, Amp by x approximately 1.9, and the Amp-Freq product (AFP) by x approximately 3.5. Under isobaric conditions, the pressure elevation from 0.5 to 10 cmH(2)O in the absence of SP decreased Amp by x approximately 0.6 and increased Freq by x approximately 1.8. SP caused a modest increase in Amp, a robust increase in Freq at all pressures, and shifted the AFP-pressure relationship upward and leftward. Therefore, SP has substantial positive inotropic and chronotropic effects on rat lymphatic muscle, improving pump efficiency independent of the effects of preload and broadening of the working range of the lymphatic pump.     

TGF-beta1 is a negative regulator of lymphatic regeneration during wound repair

Although clinical studies have identified scarring/fibrosis as significant risk factors for lymphedema, the mechanisms by which lymphatic repair is impaired remain unknown. Transforming growth factor -beta1 (TGF-beta1) is a critical regulator of tissue fibrosis/scarring and may therefore also play a role in the regulation of lymphatic regeneration. The purpose of this study was therefore to assess the role of TGF-beta1 on scarring/fibrosis and lymphatic regeneration in a mouse tail model. Acute lymphedema was induced in mouse tails by full-thickness skin excision and lymphatic ligation. TGF-beta1 expression and scarring were modulated by repairing the wounds with or without a topical collagen gel. Lymphatic function and histological analyses were performed at various time points. Finally, the effects of TGF-beta1 on lymphatic endothelial cells (LECs) in vitro were evaluated. As a result, the wound repair with collagen gel significantly reduced the expression of TGF-beta1, decreased scarring/fibrosis, and significantly accelerated lymphatic regeneration. The addition of recombinant TGF-beta1 to the collagen gel negated these effects. The improved lymphatic regeneration secondary to TGF-beta1 inhibition was associated with increased infiltration and proliferation of LECs and macrophages. TGF-beta1 caused a dose-dependent significant decrease in cellular proliferation and tubule formation of isolated LECs without changes in the expression of VEGF-C/D. Finally, the increased expression of TGF-beta1 during wound repair resulted in lymphatic fibrosis and the coexpression of alpha-smooth muscle actin and lymphatic vessel endothelial receptor-1 in regenerated lymphatics. In conclusion, the inhibition of TGF-beta1 expression significantly accelerates lymphatic regeneration during wound healing. An increased TGF-beta1 expression inhibits LEC proliferation and function and promotes lymphatic fibrosis. These findings imply that the clinical interventions that diminish TGF-beta1 expression may be useful in promoting more rapid lymphatic regeneration.     

Terminal lymphatics: the potential "lethal corner" in the distribution of tissue pO2

BACKGROUND: Terminal lymphatic fluid is the compartment furthest removed from the oxygen supply, and therefore should present the lowest pO(2) in the tissue due to oxygen consumption by the tissue and the lymphatic vessel wall. METHODS AND RESULTS: The distribution of pO(2) was determined in the tissue, the lymphatic microvessels, and arterioles and venules of the hamster chamber window model, which is studied without anesthesia with the tissue isolated from the environment. Lymphatic fluid pO(2) was measured with the phosphorescence oxygen quenching method. Small terminal lymphatic fluid pO(2) was 18.4 +/- 2.6 mmHg, and 18.0 +/- 2.4 mmHg in collecting lymphatics. Tissue pO(2) averaged 24.6 +/- 2.7 mmHg. The significant difference between tissue and intralymphatic pO(2) was due in part to the presence of an oxygen gradient across the lymphatic wall, which ranged from 3.7 +/- 1.3 mmHg for terminal lymphatics, to 6.0 +/- 1.2 mmHg for collecting lymphatics. This gradient is assumed to be due to the oxygen consumption by the cellular component of the lymphatic wall. CONCLUSION: The increased vessels wall gradient found in collecting lymphatics was reconciled by the findings that these microlymphatic vessels tend to be contiguous to the arterioles, whereas the terminal lymphatics are dispersed in the tissue. These findings indicate that terminal lymphatic present the lowest oxygen tension in the tissue, and therefore are the locations at risk to develop anoxia when the microvascular oxygen supply becomes limited.     

肿瘤淋巴管入侵与无淋巴结转移膀胱癌复发及预后的相关性分析

目的:分析肿瘤淋巴管入侵与无淋巴结转移膀胱癌复发和预后之间的关系。方法:选取临床资料完整的膀胱癌病例72例,分为淋巴结转移组(32例)和无淋巴结转移组(40例)。采用Spearman相关分析探讨淋巴管入侵与膀胱癌复发和预后的相关性,应用Kaplan-Meier法描绘生存曲线,Cox比例危险度模型筛选影响膀胱癌患者预后的因素。结果:在72例膀胱癌组织中,淋巴管入侵的阳性率是48.6%(35/72),淋巴管入侵的阳性率随肿瘤分期和分级增加而显著升高(P0.05);淋巴结转移组的淋巴管入侵阳性率为68.8%(22/32),显著高于无淋巴结转移的32.5%(13/40)。淋巴管入侵与膀胱癌的临床分期、分级、淋巴结转移以及无淋巴结转移膀胱癌复发均显著相关(P0.05)。淋巴管入侵阴性的患者的五年总体生存率显著高于淋巴管入侵阳性者,淋巴管入侵是无淋巴结转移膀胱癌复发和预后不良的危险因素。结论:肿瘤淋巴管入侵与膀胱癌临床分期和淋巴结转移密切相关,并影响膀胱癌患者的总体生存率,可作为无淋巴结转移膀胱癌复发和预后的预测因素。     

The Elimination of Lymphatic Filariasis: A Strategy for Poverty Alleviation and Sustainable Development - Perspectives from the Philippines

BACKGROUND: Within the Philippines areas endemic for lymphatic filariasis are in regions with the highest incidence of poverty. Out of a total of 79 provinces, 39 have a higher poverty incidence than the national average and 30 of these 39 provinces are endemic for lymphatic filariasis. DISCUSSION: Recognizing that provinces endemic for lymphatic filariasis (LF) are also the poorest provinces, the elimination of lymphatic filariasis in these areas presents significant opportunities to reduce poverty and inequalities in health. The implementation of an effective national programme for the elimination of lymphatic filariasis will provide means for sustainable development at national, local and community levels. SUMMARY: The elimination of lymphatic filariasis as a public health problem is a 20-year strategic plan for the world community, with the vision of all endemic communities free of transmission of lymphatic filariasis by 2020 and with the commitment to ensure the delivery of quality technologies and human services to eliminate lymphatic filariasis worldwide through a multi-stakeholder global alliance of all endemic countries. This global goal of elimination of lymphatic filariasis is a significant opportunity for partnerships - a world with less poverty through sustainable development and free from the scourge of lymphatic filariasis.     

Successful treatment of 19 consecutive groin lymphoceles with the assistance of intraoperative lymphatic mapping

Postoperative groin lymphoceles that fail to resolve spontaneously or with interventional therapy present a formidable problem that is associated with a high degree of morbidity. Numerous interventional methods and operative techniques have been described to treat these fluid collections, yet recurrence rates remain high. The use of lymphatic mapping has gained widespread use in the treatment of cutaneous malignancies and breast cancer and has been proven effective in delineating the course of lymphatic channels. We present here a series of 17 consecutive patients with 19 problematic groin lymphoceles who were treated with the assistance of intraoperative lymphatic mapping using isosulfan blue dye. To date there have been no recurrences and minimal morbidity associated with the technique and prescribed postoperative treatment regimen.     

Smooth muscle-endothelial cell communication activates Reelin signaling and regulates lymphatic vessel formation

Active lymph transport relies on smooth muscle cell (SMC) contractions around collecting lymphatic vessels, yet regulation of lymphatic vessel wall assembly and lymphatic pumping are poorly understood. Here, we identify Reelin, an extracellular matrix glycoprotein previously implicated in central nervous system development, as an important regulator of lymphatic vascular development. Reelin-deficient mice showed abnormal collecting lymphatic vessels, characterized by a reduced number of SMCs, abnormal expression of lymphatic capillary marker lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), and impaired function. Furthermore, we show that SMC recruitment to lymphatic vessels stimulated release and proteolytic processing of endothelium-derived Reelin. Lymphatic endothelial cells in turn responded to Reelin by up-regulating monocyte chemotactic protein 1 (MCP1) expression, which suggests an autocrine mechanism for Reelin-mediated control of endothelial factor expression upstream of SMC recruitment. These results uncover a mechanism by which Reelin signaling is activated by communication between the two cell types of the collecting lymphatic vessels--smooth muscle and endothelial cells--and highlight a hitherto unrecognized and important function for SMCs in lymphatic vessel morphogenesis and function.     

The clinical importance of micrometastases within the lymphatic system in patients after total gastrectomy

Background

In spite of radical gastrectomy with resection of the lymphatic system, where no metastases are found during histopathological examination, about 30% of patients have relapse of the neoplastic process. This situation may be caused by micrometastases or isolated neoplastic cells in the lymphatic system which were not identified during a standard histopathological examination.

Aim

The aim of the study was to evaluate the clinical importance of micrometastases within the lymphatic system in patients with gastric cancer.

Materials and methods

A group of 20 patients treated for gastric cancer were subjected to retrospective analysis. Of all the patients who underwent surgery, a group with tumours classified as T1 or T2 was selected. No metastases within the lymphatic system were found in the standard evaluation – N0 mark. Paraffin-embedded blocks of lymph nodes were cut and new specimens were made, which were then stained again by means of immunohistochemistry. Antibodies against cytokeratin AE1/AE3 were used.

Results

A total of 319 lymph nodes were assessed in 20 patients in an H + E examination. After the immunohistochemical examination, micrometastases within the lymphatic system were found in 4 (20%) patients and isolated neoplastic cells in other 4 (20%) patients.

Conclusion

On the basis of numerous publications and our own material, we think that the presence of micrometastases may be related to a worse prognosis. The clinical importance of micrometastases within the lymphatic system in patients after total gastrectomy.     

Dynamic imaging of lymphatic vessels and lymph nodes using a bimodal nanoparticulate contrast agent

BACKGROUND: Evaluation of lymphedema and lymph node metastasis in humans has relied primarily on invasive or radioactive modalities. While noninvasive technologies such as magnetic resonance imaging (MRI) offer the potential for true three-dimensional imaging of lymphatic structures, invasive modalities, such as optical fluorescence microscopy, provide higher resolution and clearer delineation of both lymph nodes and lymphatic vessels. Thus, contrast agents that image lymphatic vessels and lymph nodes by both fluorescence and MRI may further enhance our understanding of the structure and function of the lymphatic system. Recent applications of bimodal (fluorescence and MR) contrast agents in mice have not achieved clear visualization of lymphatic vessels and nodes. Here the authors describe the development of a nanoparticulate contrast agent that is taken up by lymphatic vessels to draining lymph nodes and detected by both modalities. METHODS: A unique nanoparticulate contrast agent composed of a polyamidoamine dendrimer core conjugated to paramagnetic contrast agents and fluorescent probes was synthesized. Anesthetized mice were injected with the nanoparticulates in the hind footpads and imaged by MR and fluorescence microscopy. High resolution MR and fluorescence images were obtained and compared to traditional techniques for lymphatic visualization using Evans blue dye. RESULTS: Lymph nodes and lymphatic vessels were clearly observed by both MRI and fluorescence microscopy using the bimodal nanoparticulate contrast agent. Characteristic tail-lymphatics were also visualized by both modalities. Contrast imaging yielded a higher resolution than the traditional method employing Evans blue dye. MR data correlated with fluorescence and Evans blue dye imaging. CONCLUSION: A bimodal nanoparticulate contrast agent facilitates the visualization of lymphatic vessels and lymph nodes by both fluorescence microscopy and MRI with strong correlation between the two modalities. This agent may translate to applications such as the assessment of malignancy and lymphedema in humans and the evaluation of lymphatic vessel function and morphology in animal models.     

Emilin1 deficiency causes structural and functional defects of lymphatic vasculature

Lymphatic-vasculature function critically depends on extracellular matrix (ECM) and on its connections with lymphatic endothelial cells (LECs). However, the composition and the architecture of ECM have not been fully taken into consideration in studying the biology and the pathology of the lymphatic system. EMILIN1, an elastic microfibril-associated protein, is highly expressed by LECs in vitro and colocalizes with lymphatic vessels in several mouse tissues. A comparative study between WT and Emilin1-/- mice highlighted the fact that Emilin1 deficiency in both CD1 and C57BL/6 backgrounds results in hyperplasia, enlargement, and frequently an irregular pattern of superficial and visceral lymphatic vessels and in a significant reduction of anchoring filaments. Emilin1-deficient mice also develop larger lymphangiomas than WT mice. Lymphatic vascular morphological alterations are accompanied by functional defects, such as mild lymphedema, a highly significant drop in lymph drainage, and enhanced lymph leakage. Our findings demonstrate that EMILIN1 is involved in the regulation of the growth and in the maintenance of the integrity of lymphatic vessels, a fundamental requirement for efficient function. The phenotype displayed by Emilin1(-/-) mice is the first abnormal lymphatic phenotype associated with the deficiency of an ECM protein and identifies EMILIN1 as a novel local regulator of lymphangiogenesis.     

Anatomy and topography of external iliac lymph nodes in adults]

The investigation of the external iliac lymph nodes has been performed in 152 preparations of corpses of mature persons of both sex, who died from causes not connected with any disease of the lymphatic system, lower extremities and pelvic organs. The external iliac lymph nodes and their afferent and efferent lymphatic vessels have been revealed by means of interstitial injection of the lower extremities and pelvic organs, as well as by means of direct injection of Gerota mass into the lymphatic vessels. Form, amount, dimensions and topography of common iliac lymph nodes have been studied. Lymphatic vessels, running from certain parts and organs of the body to various subgroups of the external iliac lymph nodes have been described, as well as efferent lymph vessels of these nodes. The external iliac lymph nodes are constant formations; the largest of them--lymph nodes of the lacuna--are nodes of the I step for the lower extremity lymph vessels. In 54% of cases in persons of both sex positive (right-sided) asymmetry has been revealed. Total amount of the iliac lymph nodes prevails in men, while their size is greater in women. The size of these nodes in persons of both sex is greater to the left than to the right. There are connections (in 3% of cases) between the external iliac lymph nodes and aortal and lumbar nodes of the opposite side.     

The anlage of the duodenal lymphatic bed: morphogenetic prerequisites, structure and importance

The anlage of the duodenal lymphatic bed takes place on the 3d month of the human intrauterine life. In the intestinal villi there are chyle sinuses, that fuse into presumptive lymphatic vessels, having capillary structure, when they get out of the villi. Intraorganic vessels turn into extraorganic ones, they flow into the pancreatoduodenal lymphatic vessels. In their lumens stromal anlage of the lymphatic nodes are formed as a result of invagination of the blood vessels. Development of the lymphatic bed in the duodenum preceded with formation of intestinal villi (this contributes to absorption of the intestinal content) and deformity of the superior mesenteric vein (this probably makes difficult the organ's drainage). The situation is solved owing to the lymphatic bed anlage. It is, evidently, formed by means of switching off a part of embryonal veins from the blood stream.