Spontaneous reanastomosis between lymphatic vessels following syngeneic transplantation of the small intestine in the rat

Spontaneous lymphvascular reanastomosis (SLR) following small bowel transplantation in rats is of clinical relevance for the resorption of long chain fatty acids. Detailed morphological and molecular data concerning the process of lymphvascular reanastomosis are not available in the literature. In this study SLR was investigated using microradiology and scanning electron microscopy. Between the 8th and 21st postoperative days following transplantation SLR does not occur between the intestinal trunk of the transplant and the thoracic duct of the recipient. Instead, an indirect connection was observed between the inserted advential lymphatic vessels of the mesenteric artery and lymphatic vessels of the aorta or ductus deferens, which are connected with the thoracic duct.     

The cytotoxic activity of lymphocytes from human lymph in vitro

The in vitro cytotoxicity and DNA synthesis of thoracic duct and blood lymphocytes from four patients have been studied on the 1st day of drainage. Three patients were being drained as a pretreatment for kidney transplantation and one had myasthenia gravis. In one patient lymphocytes were obtained from a lymphatic fistula in the groin and from the blood 5 weeks after drainage began. Lysis of tissue culture cells (Chang cells) in the presence of PHA or antiserum to target cell antigens was quantitated by [⁵¹Cr]chromate release.

Lymphocytes from lymph were at best poorly cytotoxic to antibody-treated target cells under conditions where purified blood lymphocytes from the same donors had normal lytic activity. PHA-induced cytotoxicity by lymph-borne lymphocytes was noted but was considerably weaker than that of blood lymphocytes. In contrast, incorporation of [¹⁴C]thymidine into DNA of thoracic duct lymphocytes after stimulation with PHA was about 60% of that of the patients' blood lymphocytes. The DNA synthesis of thoracic duct lymphocytes induced by PPD or allogeneic lymphocytes was as good as that of blood lymphocytes. The mitotic response to PHA by lymphocytes from the lymph was reduced after two weeks drainage.

It is assumed that the number of effector cells and/or supporting cells in antibody-induced cytotoxicity in thoracic duct lymph is too small to induce target cell lysis under the present experimental conditions. Moreover, our data indicate that PHA-induced and antibody-mediated cytotoxicity are at least partly mediated by different lymphocyte subpopulations.

     

Immunohistochemical differentiation between lymphangiographically verified lymphatic vessels and blood vessels

Summary In order to investigate the antigen profile in human lymphatic vessels when compared with blood vessels, postmortem retrograde lymphangiography was done via the thoracic duct on six patients. Formalin fixed, paraffin embedded tissue was stained immunohistochemically for Factor VIII-Related antigen (F VIII R:Ag), with Ulex Europaeus 1 lectin (UEA-1) and for laminin. The results show that the endothelium of blood vessels and lymphatics at all levels of the lymphatic system react positively following staining for Factor VIII-R:Ag and with UEA-1 lectin. The staining for F VIII R:Ag was generally weaker in the endothelial cells lining lymphatic vessels. Staining for the basement membrane component laminin can be used to distinguish lymphatic capillaries and smaller lymphatic collecting vessels from blood vessels.     

Mediastinal lymphatic efferents from the diaphragm

The prognosis of non small cell lung cancer (NSCLC) invading the diaphragm is poor, probably due to the richness of the lymphatic drainage of the diaphragm. The aim of this study was to determine mediastinal lymphatic efferents from the diaphragm. The diaphragms of 20 adult cadavers (77-104 years) were injected with a dye (modified Gerota's medium) to permit the lymph vessels to be catheterised and then dissected. Each stage of the dissection was described and photographed: 23 injections on the right and 25 on the left. Diaphragmatic lymph vessels passed to one of three lymph centres: posterior (paraaortic nodes, n = 16), anterior (juxtasternal nodes, n = 16) and mediastinal (visceral nodes, n = 16). From these lymph centres arose ascending lymph pathways: posteriorly to the thoracic duct (8/16), anteriorly along the internal thoracic vessels (10/16) and in the mediastinum to the peritracheobronchial nodes (6/10). Lymphatics from the diaphragm are abundant and drain towards mediastinal node lymph centres connecting to the blood stream via the thoracic duct. These lymph pathways are common with those of the pulmonary segments. Poor prognosis of NSCLC invading the diaphragm may be explained by the common lymphatic drainage of both the lung and diaphragm.     

The use of Thiel embalmed human cadavers for retrograde injection and visualization of the lymphatic system

In order to provide an alternative for fresh frozen specimens to map the lymphatic system, the possibility of using Thiel embalmed specimens for this purpose was explored. The thoracic duct was used to investigate if retrograde injection of contrast agent was possible in Thiel embalmed specimens and to verify up to which diameter lymphatic vessels could be reconstructed and rendered in 3D, after CT scanning. 3D renderings were used for digital diameter measurement, to determine the smallest lymphatic diameter that could still be visualized on CT. Finally, the contrast agent concentration was adapted based on the findings during image reconstruction and 3D rendering. All Thiel embalmed specimens proved suitable for retrograde injection of contrast agent into the thoracic duct and all 3D renderings perfectly overlapped with the dissection pictures. The smallest diameter of contrast filled lymphatics that could be reconstructed and rendered in 3D was 0.23 mm. Increasing the concentration of barium sulfate from 10 to 50% reduced the postprocessing time needed to render a “clean” 3D structure, following automatic segmentation based on grey values, by 95%. The authors would recommend the use of Thiel embalmed specimens for mapping the lymphatic system, as these specimens do not show the rapid putrefaction that occurs in fresh frozen specimens, thus greatly facilitating experimental planning.     

Suprarenal gland lymphatic drainage

The gross and microscopic anatomy of the suprarenal gland lymphatic system was studied in post mortem specimens and specimens in which the venous system was injected with blue latex solution. Extensive subserous lymphatic networks overlie the suprarenal gland. Deep to these networks are the lymphatic vessels proper of the suprarenal gland. These vessels lie within the suprarenal gland capsule and communicate with the subserous lymphatic network. Their primary routes of drainage, however, are directed medialward, passing to the thoracic duct cr cisterna chyli either directly or by way of regional lymph nodes. A few capsular lymphatic vessels extend toward the diaphragm or the kidney. The regional lymph nodes are small, few in number and situated at the lower medial aspect of the gland. Microscopic examination of serially sectioned suprarenal glands revealed a complete absence of lymphatic vessels in the cortical and medullary parenchymal tissue. Lymphatic vessels were found only in the capsule and in the adventitia of the central vein and its major tributaries. A close association between capsular lymphatic vessels and veins was noted and in a number of specimens capsular lymphatic vessels were traced to the inferior vena cava where they assumed a close relationship with vasa vasorum.     

Migration pathways of recirculating murine B cells and CD4+ and CD8+ T lymphocytes

Migration pathways of B cell and CD4⁺ and CD8⁺ T cell subsets of murine thoracic duct lymphocytes (TDL) were mapped. Per weight, the spleen accumulated more TDL than any other organ, regardless of lymphocyte subset. Spleen autoradiographs showed early accumulations of TDL in marginal zone and red pulp. Many TDL exited the red pulp within 1 hr via splenic veins. The remaining TDL entered the white pulp, not directly from the adjacent marginal zone but via distal periarterial lymphatic sheaths (dPALS). From dPALS, T cells migrated proximally along the central artery into proximal sheaths (pPALS) and exited the white pulp via deep lymphatic vessels. B cells left dPALS to enter lymphatic nodules (NOD), then also exited via deep lymphatics. T cells homed to lymph nodes more efficiently than B cells. Lymphocytes entered nodes via high-endothelial venules (HEV). CD4⁺ TDL reached higher absolute concentrations in diffuse cortex than did CD8⁺ T cells. However, CD8⁺ TDL moved more quickly through diffuse cortex than did CD4⁺ TDL. B cells migrated from HEV into NOD. Both T and B TDL exited via cortical and medullary sinuses and efferent lymphatics. A migration pathway across medullary cords is described. All TDL subsets homed equally well to Peyer's patches. T TDL migrated from HEV into paranodular zones while B cells moved from HEV into NOD. All TDL exited via lymphatics. Few TDL entered zones beneath dome epithelium. All subsets were observed within indentations in presumptive M cells of the dome epithelium.     

The efficacy of closed-circuit extracorporeal filtration of thoracic duct lymph as a means of lymphocyte depletion

Thoracic duct-venous shunts were prepared in yearling calves. A lymph filtration apparatus was then inserted into the system, thus allowing for the removal of thoracic duct lymphocytes via closed-circuit extracorporeal filtration. Long term thoracic duct flow rates and lymphocyte concentrations averaged 20 litres per day and 22,000/mm³ respectively. Filtration proved very effective in removing cells from the thoracic duct lymph. Filtration periods of 9–11 days removed an average of nearly 2 × 10¹² lymphocytes. Such periods of cell removal decreased the thoracic duct cell concentration to nearly 10% of the original level. Six weeks following cessation of filtration, this level had risen to only 29%. It is concluded that closed-circuit extracorporeal filtration of thoracic duct lymph offers an important and effective new tool for achieving lymphocyte depletion.     

Origins and pathways of fluid entering sublobular lymphatic vessels in cat livers

The liver, which produces a large volume of lymph, has a lymphatic system which can be classified into three categories: portal, sublobular, and superficial lymphatic vessels. As little is known about the origin and pathways of sublobular lymph, this study demonstrates pathways of interstitial fluid flowing into sublobular lymphatic vessels. Livers from cats whose thoracic ducts were either ligated or non-ligated were examined by light-, transmission electron- and scanning electron-microscopy (SEM). Complete ligation of the thoracic duct caused significant dilation of the hepatic sinusoids, the space of Disse, and channels passing through the limiting plate. Sublobular interstitial space and sublobular lymphatic vessels were also expanded. The channels between hepatocytes forming the limiting plate contained collagen fibers, and connected the space of Disse with a sublobular interstitial space. The alkali-water maceration/SEM confirmed that collagen fibers traversing the layer of the limiting plate independently of blood vessels connected collagen fibers in the space of Disse with those in the sublobular space. Complete ligation of the thoracic duct also showed an accumulation of mast cells and plasma cells in the sublobular interstitial space. Our data suggest that fluid in the space of Disse flows along collagen fibers in channels traversing the limiting plate as well as those along the sinusoids and central veins that drain into sublobular veins, and enters the sublobular interstitial space to finally lead into sublobular lymphatic vessels. Our study has also shown that hepatic lymphostasis causes the accumulation of mast cells and plasma cells in the sublobular interstitial space, which may be involved in lymphangiogenesis and fibrogenesis.     

Lymph Circulation in the Liver

The liver produces a large amount of lymph, which is estimated to be 25 to 50 % of lymph flowing through the thoracic duct. The hepatic lymphatic system falls into three categories depending on their locations: portal, sublobular, and superficial lymphatic vessels. It is suggested that 80 % or more of hepatic lymph drains into portal lymphatic vessels, while the remainder drains through sublobular and capsular lymphatic vessels. The hepatic lymph primarily comes from the hepatic sinusoids. Our tracer studies, together with electron microscopy, show many channels with collagen fibers traversing through the limiting plate and connecting the space of Disse with the interstitial space either in the portal tracts, or around the sublobular veins. Fluid filtered out of the sinusoids into the space of Disse flows through the channels traversing the limiting plate either independently of blood vessels or along blood vessels and enters the interstitial space of either portal tract or sublobular veins. Fluid in the space of Disse also flows through similar channels traversing the hepatocytes intervening between the space of Disse and the hepatic capsule and drains into the interstitial space of the capsule. Fluid and migrating cells in the interstitial space pass through prelymphatic vessels to finally enter the lymphatic vessels. The area of the portal lymphatic vessels increases in liver fibrosis and cirrhosis and in idiopathic portal hypertension. Lymphatic vessels are abundant in the immediate vicinity of the hepatocellular carcinoma (HCC) and liver metastasis. HCCs expressing vascular endothelial growth factor‐C are more liable to metastasize, indicating that lymphangiogenesis is associated with their enhanced metastasis. Anat Rec, 291:643–652, 2008. © 2008 Wiley‐Liss, Inc.     

胸导管结扎对大鼠脂质代谢和胰组织结构的影响

目的:探讨胸导管结扎对脂质代谢的影响,揭示淋巴回流障碍诱发胰组织的显微和超微结构变化.方法:SD大鼠随机分为假手术对照组和结扎胸导管模型组.术后6个月取静脉血标本进行血脂检测;部分胰组织标本,H-E和刚果红染色光镜观察;部分胰组织进行透射电镜观察.结果:(1)模型组大鼠游离脂肪酸和甘油三酯浓度明显下降,胆固醇浓度无显著变化.(2)光镜观察显示模型组大鼠的胰腺小叶间隙增宽,脂肪堆积和淋巴管扩张.(3)透射电镜观察显示模型组大鼠的胰岛细胞间隙增宽,细胞间隙及细胞内可见大量脂滴样物质、红细胞和胶原原纤维样结构.结论:胸导管结扎可引起胰腺结构变化和影响胰腺的内、外分泌功能.     

A computer model of the lymphatic system

A mathematical model of the whole body lymphatic network, which simulates the lymph propulsion along the network from the periphery through the thoracic duct into the venous system, is developed using the fundamental conservation laws and current notions of lymphology. Only the major lymphatic vessels are considered. The set of mathematical equations are then translated into a series of FORTRAN statements for the purpose of digital computer simulation of the pressure and flow patterns along the network. The model analysis revealed interesting characteristics of lymphatic contractility at various points along the network.     

IgA-containing plasma cells in the lamina propria of the gut: failure of a thoracic duct fistula to deplete the numbers in rat small intestine.

The quantitative importance of the traffic of large lymphocytes through the thoracic duct to the maintenance of the IgA-containing plasma cell population of the lamina propria of the gut was examined by draining the thoracic duct for periods of time up to 10 days. Contrary to the expectation that IgA-secreting plasma cell numbers in the small intestine would decline exponentially with a half-time of approximately 5 days, the numbers of cells remained relatively constant after an initial decline in the first 4 days of lymphatic diversion. Results of in vivo pulse labeling with tritiated thymidine suggest that plasma cell numers are maintained by cell proliferation within the intestinal lamina propria, and that this is a compensatory mechanism brought into play by removal of the normal supply of precursors from the thoracic duct. The compensatory local recruitment of dividing plasma cell precursors principally involves those committed to IgA synthesis. It is suggested that thoracic duct lymph diversion calls into play a local mechanism to make up the deficit of plasma cell precursors lost in the lymph. This may be an accentuation of normal regulation of IgA synthesis in the lamina propria, and suggests that the homing of thoracic duct large lymphocytes is not the only source of renewal of gut plasma cells.     

Significance of features of the projection of the cervical part of the thoracic duct onto the left sternocleidomastoid muscle for performing operations involving video support

To work out practical recommendations for using videosupport projection of cervical part of the thoracic duct on sternoclaidomastoid muscle was determined in 158 corpses of adults. Surgical access to the thoracic duct is available using common macrosurgical equipment until the moment of visualization of major lymphatic corrector, although it is reasonable to involve videosupport at following stage with the camera of videoendosurgical kit adjusted in inferior margin of the wound. This allows to perform all the necessary actions to expose cervical part of the thoracic duct and to correct them according to video information on the monitor.     

Contraction-initiated NO-dependent lymphatic relaxation: a self-regulatory mechanism in rat thoracic duct

The objectives of this study were to evaluate the physiological importance of the flow and shear generated by phasic contractions of lymphatic vessels and the mechanisms responsible for the influences of such shear on lymphatic pumping. Lymphatic segments of the rat thoracic duct were isolated, cannulated and pressurized. The diastolic diameters were measured in phasically non-active segments. The diastolic and systolic diameters, half-relaxation time (HRT), contraction frequency, ejection fraction and fractional pump flow were determined in phasically active segments. Since imposed flow was excluded, flow and shear occurred only as a result of the intrinsic contractions in phasically active segments whereas in phasically non-active segments contraction-generated flow and shear were absent. The influences of incrementally increased transmural pressure (from 1 to 5 cmH₂O) were examined in control conditions and after NO synthase blockade ( l -NAME 10⁻⁴ m ) or cyclooxygenase blockade (indomethacin 10⁻⁵ m ). The spontaneous phasic contractions produced a flow-dependent diastolic relaxation. This reduction of the lymphatic tone is a regulatory mechanism that maintains pumping in thoracic duct in an energy-saving/efficient mode: it improves diastolic filling (enhanced lusitropy – lowering HRT), makes lymphatic contractions stronger (enhanced inotropy – higher contraction amplitude) and propels more fluid forward during each contraction (elevated ejection fraction) while decreasing contraction frequency (reduced chronotropy). The findings also demonstrated that the NO pathway, not the cyclooxygenase pathway is responsible for this reduction of lymphatic tone and is the prevailing pathway responsible for the self-regulatory adjustment of thoracic duct pumping to changes in lymph flow pattern.     

Deep splenic lymphatic vessels in the mouse: A route of splenic exit for recirculating lymphocytes

A study of pathways of lymphocyte migration through mouse spleen revealed lymphatic channels closely following arteries in trabeculae and white pulp. Because there is no detailed record of the layout of deep splenic lymphatics in the mouse, or other species, we present our observations in this paper, relating our findings to normal migratory pathways of lymphocytes through the spleen. Lymphatics draining the spleen are so inconspicuous that they often are not mentioned in anatomical discussions. The data presented clearly demonstrate (1) the existence and layout of deep lymphatic vessels in the mouse spleen, and (2) that migrating lymphocytes exit white pulp via these lymphatic vessels. CD4⁺ and CD8⁺ T cell subsets migrated proximally along the central artery from distal (dPALS) to proximal periarterial lymphatic sheaths (pPALS) and exited via deep lymphatic vessels that originate there. B cells migrated from dPALS to enter lymphatic nodules (NOD), thus segregated from T cells. B cells then migrated toward and exited via deep lymphatics. The appearance of labelled lymphocytes in lymph coincided with their disappearance from white pulp compart-ments. Labelled T cells were observed in splenic lymphatics as early as 1 hr after intravenous infusion but took, on average, about 6 hr. B cells took somewhat longer. Thus T and B cells entered and left white pulp through shared pathways, but took divergent intermediate routes through dedicated zones, pPALS for T cells, NOD for B cells.     

Fate of Autogenous Canine Lymphocytes after Injection into an Afferent Lymphatic of the Popliteal Lymph Node

Dog thoracic duct lymphocytes were labeled in vitro with ³H-uridine and infused into an afferent lymphatic of the popliteal lymph node of the same dog. Ten minutes after infusion nearly all the injected radioactivity was recovered from the lymph node. An effect of infusion flow rate on the percentage of cells retained by the lymph node was observed ½ to 3½ hours after infusion, and was probably mediated by the tendency of the node to become edematous after infusions at a rate exceeding 0.045 ml/min. Edematous nodes retained 83.7% of the cells, as compared to 47.5% for nonedematous nodes. As early as 30 minutes after infusion a small amount of ³H-radioactivity was found in the spleen and thoracic duct lymph. The deep iliac and paraaortic nodes on the side of the infusion contained significant amounts of ³H-radioactivity, while negligible amounts were detected in the contralateral popliteal node at any time. The intranodal localization of the ³H-labeled cells was studied by radioautography. All labeled cells remained intrasinusoidal during the first 4 hours after infusion. At 9 and 21 hours some labeled cells were located in the extrasinusoidal parenchymal lymphoid tissue of the cortex and the medulla, but the majority still remained intrasinusoidal.     

Lymphatic development in mouse small intestine.

Lymphatic vessels in the small intestine serve as essential conduits for the absorption and transport of lipids from the intestine to the thoracic duct. Although the morphology and function of the intestinal lymphatic vasculature are well known, little is known about the embryonic development of these vessels. In this study, we examined development of lymphatic and blood vasculatures in the intestinal tube during mouse embryonic development by immunostaining with recently discovered molecular markers for lymphatic endothelial cells: LYVE-1, VEGFR3, Prox-1, and podoplanin. Immature lymphatics became detectable in mesentery, but not in intestinal tube, around E13.5-E14.5, while organized lymphatic vessel plexuses and capillaries were observed in intestinal tube and villi around E17.5. These lymphatic plexuses and capillaries in the intestinal tube appeared to be formed through an active branching process associated with activation of VEGFR3 and involvement of LYVE-1+ macrophages. Our data also reveal that the lymphatic vessels in the intestinal tube, unlike the blood vessels, have not originated from the mesoderm of intestine. All lymphatic vessels in the intestinal tube originated by extension of mesenteric lymphatic vessels through an active branching process. Although the formation of lymphatic vessels follows the formation of blood vessels in the intestine, a mature lymphatic vasculature is formed before birth. Together, our study reveals the temporal and spatial windows of intestinal lymphatic development during embryonic development in mouse.