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At least 145 records · Page 8Linked to original sources
PubMed1984

Scanning- and transmission electron-microscopic study of lymphatic vessels in the splenic white pulp of the macaque monkey.

The fine structure of the lymphatic vessels in splenic white pulp of the macaque monkey was studied by scanning and transmission electron microscopy. Lymphatic vessels were slit-like or widened channels which extended along central arteries and their large branches. The walls of the vessels were very thin in comparison with those of nearby arteries. They were composed only of a layer of endothelium supported by underlying reticular cells. Endothelial cells were mostly ribbon-like and extended along the long axis of the vessels. Perikarya of the endothelial cells were slightly protruded into the lumen. The thin peripheral cytoplasm showed smooth surfaces, except for some tiny processes, especially at boundaries between adjacent cells. The basal surface of the endothelial cells was attached to the lattice of reticular cell processes forming the framework of the white pulp. Basal laminae in strands were intercalated between endothelial cells and reticular cells. Perforations were often seen through the endothelial cell cytoplasm. Lymphocytes or processes of macrophages seen in the perforations were considered to be in migration. Large patent openings through the endothelium were not observed. The wall structure of the lymphatic vessels in the splenic white pulp suggests that lymphocytes in the white pulp may move directly into the lymph flow, in addition to moving into the blood flow via the vascular sinuses.

Animals↗
PubMed1979

Scanning electron microscopy of collecting lymphatic vessels and their comparison to arteries and veins.

The morphology of canine thoracic duct and peripheral collecting lymphatics was determined using light microscopy together with scanning and transmission electron microscopy (SEM and TEM). The thoracic duct was compared to the thoracic aorta and to the vena cava. Luminal surface detail was determined using the secondary imaging mode of the SEM. Subsurface nuclear and connective tissue detail was determined using back-scattered electron imagining combined with Willard's modification of Gomori's Methenamine Silver Stain. Central and peripheral lymphatic vessels have surface morphology distinct from either arteries or veins. The endothelial cell density in lymphatic vessels is less than in arteries or veins. The nuclear chromatin of lymphatic endothelial cells is coarsely granular and evenly distributed. This contrasts with nuclei from arteries or veins in which the chromatin is segmented. The distribution and orientation of lymphatic subsurface connective tissue fibers also differs from that seen in arteries and veins. It is concluded that canine lymphatic vessels have a unique surface and subsurface morphology and can be unequivocally identified by SEM.

Animals↗
PubMed1980

[Normal anatomy and topography of the hindlimb lymphatic vessels of white rats].

Topographic-anatomical investigation of lymphatic vessels in hind limbs has been performed in mature healthy white rats (males, 200-220 g). While studying 25 preparations of the pelvis and 50 hind limbs, it has been stated that the lymphatic bed of the white rat hind limb consists of superficial (situated in two layers) and deep lymphatic vessels, their number, transversal section and topography at different levels being strictly regular and to a certain extent dependent on a specific structure of fascia of the extremity and on a peculiar topography of its blood vessels.

Animals↗
PubMed1990

An investigation of lymphatic vessels in the feline dental pulp.

The existence of lymphatic vessels in the dental pulp has been a matter of continuing controversy. We have now used light microscopy to examine semithin transverse sections of perfusion-fixed incisors and canines in cats. Lymphatics were found in all the teeth studied. In most teeth they were present in the coronal, middle, and apical regions of the pulp; but in a few they were lacking coronally and in the middle. Within individual teeth, lymphatics were found in the subodontoblastic zone or more centrally in the pulp; but none were found in the odontoblast layer or in the pulp horns. Vessels located by light microscopy were subsequently examined by transmission electron microscopy. Their ultrastructural features were typical of lymphatics and included irregular, attenuated endothelium with adjacent cells joined in different ways. Occasional gaps connected the extracellular spaces with their lumens, and abluminal endothelial projections appeared to form open end bulbs. There was very little basement membrane, but anchoring filaments were found near the abluminal surface of the endothelium and near collagen fibrils. The total cross-sectional area of lymphatic vessels was measured in semithin sections and, with pulp area, increased from the coronal region to the middle. However, both areas decreased from the middle to the apical region suggesting either that lymph flows faster as it reaches the foramens of the apical delta or that some vessels leave the tooth through lateral root canals. Using the methods of light and transmission electron microscopy, therefore, we have shown that pulp lymphatic vessels exist. Questions remain, however, about their distribution within teeth, variations between teeth, and routes of exit from teeth.

Animals↗
PubMed2004

Visualization of lymphatic vessels through NF-kappaB activity.

The molecular biology of lymphatics is only rudimentary owing to the long-standing absence of specific markers, and scanty is the information regarding bladder lymphatic vessels. By using mice with a reporter gene for nuclear factor kappaB (NF-kappaB) activity (kappaB-lacZ) in combination with immunohistochemical staining with a specific lymphatic marker (LYVE-1), we show, for the first time, that NF-kappaB is constitutively active in lymphatic endothelium in the urinary bladder, uterus, intestine, heart, and airways. Tie2-lacZ mice confirmed that the structures observed in kappaB-lacZ mice were not blood vessels. In addition, acute instillation of lipopolysaccharide (LPS) or tumor necrosis factor alpha (TNF-alpha) into the kappaB-lacZ mouse bladder revealed the capacity of this transgenic in reporting inducible NF-kappaB activity. Our findings demonstrate an overriding constitutive NF-kappaB activity in the lymphatic system. They also provide a working model for detecting lymphatic vessels and evoke testable hypotheses regarding the role of lymphatic vessels in health and disease.

Animals↗
PubMed2006

Lymphatic vessel density in the neoplastic progression of Barrett's oesophagus to adenocarcinoma.

BACKGROUND: Oesophageal adenocarcinoma is an aggressive neoplasm with poor prognosis as a result of early lymph node metastasis. AIMS: To measure lymphatic vessel density (LVD) in the neoplastic progression from Barrett's metaplasia to adenocarcinoma and determine whether LVD can predict the risk of cancer. In addition, to correlate LVD with lymph node metastasis and assess whether LVD could be used as a prognostic indicator for outcome or survival. METHODS: LVD and microvascular density (MVD) were assessed after immunohistochemical staining of vessels in Barrett's metaplasia, dysplasia, and adenocarcinoma tissues and were correlated with clinicopathological features. RESULTS: LVD was significantly reduced in adenocarcinoma, being half that seen in normal stomach/oesophagus or metaplasia/dysplasia. LVD did not correlate with tumour grade, stage, or clinical outcome; however, patients who had either lymph node metastasis or invasion of tumour cells into peritumorous lymphatic vessels had a significantly worse overall survival. MVD was also assessed as a prognostic marker; its increase appeared to be linked more with the development of Barrett's metaplasia than adenocarcinoma. CONCLUSIONS: The reduction in lymphatic vessel numbers was not useful for determining disease outcome in the patient group studied. It is the entry of tumour cells into pre-existing peritumorous lymphatic vessels that confers a significantly worse overall survival.

Adenocarcinoma↗
PubMed2006

Lymphatic vessels in pancreatic islets implanted under the renal capsule of rats.

Transplantation of pancreatic islets necessitates an engraftment process, including revascularization of the graft. Studies of graft vasculature have demonstrated that islets become revascularized during the first post-transplant week through an angiogenic process. If this also involves lymphatic vessels is unknown. The aim of the present study was to functionally evaluate if lymphatic vessels, which are absent in endogenous islets, form after islet transplantation. To achieve this, inbred Wistar-Furth rats were transplanted with 250 syngeneic islets under the renal capsule. Intra-vital microscopy of the graft in combination with interstitial injection of Evans Blue was performed 1 week, 1 month or 9-12 months later. In all animals studied, there was drainage through intra-graft lymphatic capillaries emptying into larger lymphatic vessels associated with the renal capsule. The number was slightly lower 1 week post-transplantation. Most of the lymphatic capillaries were present in the graft stroma, rather than interspersed among the endocrine cells. In some animals, we were able to demonstrate dye in regional lymph nodes. We conclude that unlike endogenous islets, islet grafts develop a lymphatic drainage. Its functional importance and characteristics remain to be established. However, it can be speculated that immune reactions may be facilitated by the presence of lymphatic vessels.

Animals↗
PubMed1997

Cervical venous anastomoses of pulmonary lymphatic vessels.

The aim of this study was to describe in detail the anastomoses between the pulmonary lymphatic vessels and the veins of the neck so as to better understand their role in certain aspects of thoracic surgery. The lymphatic vessels of 687 pulmonary segments in 360 cadavers were injected. A detailed study of the proximal end of the right paratracheal, right tracheo-esophageal, left preaortocarotid and left recurrent lymph node chains was undertaken. The results showed the absence of any major right lymphatic "vein". There were, however, many lymphatic arches draining into the jugulo-subclavian confluence ipsilaterally, and, in 10 to 15% of cases, contralaterally as well. The intertracheobronchial lymph nodes also drained into the venous confluence of the neck via direct lymphatic vessels, without lymph node relays. Finally, the left mediastinal lymph node chains were frequently found to drain into the arch of the thoracic duct (40% of cases), and reflux due to valvular incompetence at this level may account for chylous pericarditis and some cases of chylothorax after surgery.

Humans↗
PubMed2003

Pathways for movement of fluid and cells from hepatic sinusoids to the portal lymphatic vessels and subcapsular region in rat livers.

It has long been a mystery how fluid and migrating cells in the hepatic sinusoids reach lymphatic vessels in the portal tract. Here we describe previously-unknown channels that connect the space of Disse with the portal tract in the rat liver. Transmission electron microscopy was performed on livers injected with either horseradish peroxidase (HRP) or lipopolysaccharide, and scanning electron microscopy was carried out on livers macerated with KOH. Transmission electron microscopy revealed the presence of channels with collagen fibers traversing the limiting plate. A tracer study showed that HRP was in the channels as well as along inlet venules. Dendritic cells in the hepatic sinusoids or between hepatocytes of the limiting plate were also observed extending their pseudopodia through the channels in the limiting plate to the interstitial space of the portal tract. Scanning electron microscopy further showed that many channels (1-3microm in diameter) penetrated through the limiting plate independently of blood vessels and connected the space of Disse with the interstitial space of the portal tract. In addition, the portal tract possessed prelymphatic vessels that were lined with fibroblast-like cells and frequently contained dendritic cells. The initial segment of the portal lymphatic vessels opened to the interstitial tissue space. These results indicate that fluid and dendritic cells in the hepatic sinusoids probably pass through both the space of Disse and the channels traversing the limiting plate, enter the interstitial space of the portal tracts, and finally move from the prelymphatic vessels to the portal lymphatic vessels.

Animals↗
PubMed1988

Fluorescein labeling of lymphatic vessels for lymphangiography.

A simple technique for identification of pedal lymphatic vessels for lymphangiography was developed. A fluorescein-lidocaine mixture is injected subcutaneously into the foot, and within 20 minutes, local lymphatic vessels absorb the solution and fluoresce vividly under ultraviolet light. These labeled lymphatic channels are readily isolated and cannulated. The technique has proved highly successful, with no documented allergic complications after use in more than 1,000 cases.

Fluoresceins↗
PubMed2002

Abnormal lymphatic vessel development in neuropilin 2 mutant mice.

Neuropilin 2 is a receptor for class III semaphorins and for certain members of the vascular endothelial growth factor family. Targeted inactivation of the neuropilin 2 gene (Nrp2) has previously shown its role in neural development. We report that neuropilin 2 expression in the vascular system is restricted to veins and lymphatic vessels. Homozygous Nrp2 mutants show absence or severe reduction of small lymphatic vessels and capillaries during development. This correlated with a reduction of DNA synthesis in the lymphatic endothelial cells of the mutants. Arteries, veins and larger, collecting lymphatic vessels developed normally, suggesting that neuropilin 2 is selectively required for the formation of small lymphatic vessels and capillaries.

Animals↗
PubMed2005

Angiopoietin-1 promotes LYVE-1-positive lymphatic vessel formation.

Angiopoietin (Ang) signaling plays a role in angiogenesis and remodeling of blood vessels through the receptor tyrosine kinase Tie2, which is expressed on blood vessel endothelial cells (BECs). Recently it has been shown that Ang-2 is crucial for the formation of lymphatic vasculature and that defects in lymphangiogenesis seen in Ang-2 mutant mice are rescued by Ang-1. These findings suggest important roles for Ang signaling in the lymphatic vessel system; however, Ang function in lymphangiogenesis has not been characterized. In this study, we reveal that lymphatic vascular endothelial hyaluronan receptor 1-positive (LYVE-1(+)) lymphatic endothelial cells (LECs) express Tie2 in both embryonic and adult settings, indicating that Ang signaling occurs in lymphatic vessels. Therefore, we examined whether Ang-1 acts on in vivo lymphatic angiogenesis and in vitro growth of LECs. A chimeric form of Ang-1, cartilage oligomeric matrix protein (COMP)-Ang-1, promotes in vivo lymphatic angiogenesis in mouse cornea. Moreover, we found that COMP-Ang-1 stimulates in vitro colony formation of LECs. These Ang-1-induced in vivo and in vitro effects on LECs were suppressed by soluble Tie2-Fc fusion protein, which acts as an inhibitor by sequestering Ang-1. On the basis of these observations, we propose that Ang signaling regulates lymphatic vessel formation through Tie2.

Angiopoietin-1↗
PubMedDate not supplied

Fine structure of intrascrotal lymphatic vessels infected by Wuchereria bancrofti adult worms.

Lymphangiectasia represents a basic phenomenon of acute and chronic pathology in lymphatic filariasis, and the prevalence or degree of lymphatic dilation caused by filarial worms is considered an indirect measurement of the altered lymphatic function. We examined the morphological alterations of intrascrotal lymphatic vessels surgically removed from a volunteer infected by adult worms of Wuchereria bancrofti. Scanning electron microscopy revealed lymphatic vessels with an irregular endothelium and adherent flattened lymphocytes and macrophages in variable proportions. On transmission electron microscopy the lymphatic vessels showed a thin endothelium which had an irregular contour and projected several cytoplasmic processes into the lumen. Numerous micropinocytotic vesicles and collagen fibers were abundant and disorganized. The hyperplastic endothelial cells and the subendothelial fibrosis suggest that abnormal changes in these cells may play a crucial role in the development of lymphangiectasia.

Adult↗
PubMed2000

Structural organization and fine distribution of lymphatic vessels in periodontal tissues of the rat and monkey: a histochemical study.

The structural organization and fine distribution of lymphatic vessels in the periodontal tissues (gingiva, periodontium and alveolar process) were examined by light and electron microscopy using an enzyme-histochemical method. Whole mount preparations of periodontal membranes peeled from the teeth and cryostat sections of normal or decalcified tissues treated with EDTA were double-stained using 5'-nucleotidase (5'-Nase)-alkaline phosphatase (ALPase) and examined by light microscopy. This staining procedure allowed the lymphatic vessels in the periodontal tissue to be differentiated from blood vessels. Well-developed 5'-Nase-positive lymphatics were observed in the gingiva and periodontium. The histochemical aspects of 5'-Nase activity in lymphatic vessels are discussed in detail, with special reference to the supply of Mg++ ions. A network of 5'-Nase-positive lymphatics was observed in whole mount preparations of the periodontal membrane for the first time. This network was also observed in the tissue sections. More 5'-Nase-positive lymphatics were seen in the root area of the periodontium than in the cervical area. 5'-Nase-positive lymphatics in residual tissue blocks remaining after cryostat sectioning and in whole mount preparations were highlighted with good contrast and resolution on backscattered electron images produced by scanning electron microscopy. Dense granular precipitations resulting from the 5'-Nase reaction were observed on the luminal surface of the lymphatic endothelial cells as well as on the basal side but were absent in the blood vessels.

5'-Nucleotidase↗
PubMed1993

[The mechanisms of adrenergic and cholinergic effects on the lymphatic vessels of reptiles].

Adrenaline and acetylcholine were shown to induce a dose-dependent increase in tonic tension of isolated strips of the tortoise lumbar lymphatic cistern and the lizard cardinal lymphatic vessel. The affinity of adrenaline to receptors in the lizard lymphatic vessel was higher than in the tortoise lymphatic vessels, whereas the affinity of acetylcholine was higher in tortoises.

Acetylcholine↗
PubMed2006

On the transendothelial passage of tumor cell from extravasal matrix into the lumen of absorbing lymphatic vessel.

The aim of the research is the study of ultrastructural characteristics of the absorbing lymphatic vessel and of tumor cell passage through the endothelial lymphatic wall in (a) subcutaneous xenografts of T84 colon adenocarcinoma and B16 melanoma cell lines in nude mice and (b) human colorectal cancer. It was found that the tumor-associated absorbing lymphatic (TAAL) vessel has the same ultrastructural characteristics as the absorbing lymphatic vessel in normal organs, and it is provided with an endothelial wall wholly lacking a continuous basement membrane, pores, fenestrations, and open junctions. The TAAL vessel is always missing in the studied tumor masses as far as the central stroma is concerned, whereas it is always present in the peripheral area of the tumor and in the peritumoral connective tissue. The factors of extravasal matrix that play an active role in migration process of invasive phenotype tumor (IPT) cell after its detachment from tumor mass, as well as the role of cytoplasmic protrusions (pseudopod-like) in lymphatic recognition, were considered. For the first time, this study demonstrated the transendothelial passage of IPT cell inside the TAAL vessel lumen, which takes place by means of the intraendothelial channel (approximately 1.8-2.1 mum in diameter and 6.8-7.2 microm in length). This channel is to be considered a transient morphological entity organized by TAAL vessel endothelium by means of still unidentified molecular mechanisms. Therefore, it appears to be ascertained that the intraendothelial channel represents a step forward in the knowledge of the drainage into lymphatic circulation of interstitial fluid and the answer to the lack of knowledge expressed till today by researchers concerning the modality of passage of the tumor cell through the endothelial wall of the TAAL vessel.

Animals↗
PubMed2004

Expression of Toll-like receptors 2 and 4 on human intestinal lymphatic vessels.

The Toll-like receptor (TLR) is a part of the innate immune system sensing pathogen-associated molecular patterns (PAMPs). Recently, TLRs 2 and 4 have been demonstrated for the ligand engagements, which result in the induction of cytokines. Here we investigated the expression of TLRs 2 and 4 on lymphatic vessels producing cys-cys chemokine ligand 21 (CCL21) in the human small intestine. The specificity of antibodies to TLRs was tested on a human monocyte leukemia cell line, umbilical vein endothelial cells (HUVEC), and periodontal ligament fibroblasts (PDLF) with the examination for the TLR gene expression by the reverse transcription-polymerase chain reaction (RT-PCR), and lymphatic vessels were identified by antibodies for platelet-endothelial cell adhesion molecule-1 (PECAM-1) and desmoplakin. The expression of CCL21 was not clearly detected on collecting lymphatic vessels in the submucosa while it was generally observed on the central lacteals of villi and lymphatic capillaries in the lamina propria mucosae. The reaction of antibodies to TLRs 2 and 4 was also not clearly detected on collecting lymphatic vessels in the submucosa and central lacteals of villi, but generally observed on lymphatic capillaries expressing CCL21 in the lamina propria mucosae of tissue where the expression of CCL21 and TLRs was not clearly observed in blood vessels. These may suggest that the expression of CCL21, and TLRs 2 and 4 is predominantly induced in the peripheral lymphatic endothelium of the small intestinal microcirculation. The lymphatic endothelium may contribute to allow dendritic cells to home into secondary lymphoid tissue through the expression of TLRs, the ligand engagements of which result in the induction of chemokines.

Aged↗