Development of the peritoneal lymphatic stomata and lymphatic vessels of the diaphragm in mice

The generation and development of the peritoneal lymphatic stomata (PLS) and lymphatic vessels of the diaphragm were studied in mice at gestational ages from the embryonic to the postnatal period with TEM, SEM and enzyme histochemistry and the PLS data were quantitatively analyzed with computer-assisted image processing technology (Elescope image analysis software). The results showed that the diaphragmatic mesothelium was covered only by flattened mesothelial cells (FMC) at the 13th embryonic day (ED 13). At ED 15, some cuboidal mesothelial cells (CMC) and immature lymphatic stomata (NLS) were found scattered on the diaphragmatic mesothelium. The sub-peritoneal lymphatic capillaries did not appear until ED 18. However, no absorptive function was observed in NLS when trypan blue granules were injected into the peritoneal cavity. At postnatal day 1 (PND 1), the endothelial cytoplasm processes of the diaphragm lymphatic capillaries span the connective tissue fibers and the basal membrane of CMC to form the subperitoneal channels. These channels were connected with NLS and serve as the absorptive route between the peritoneal cavity and the sub-peritoneal lymphatic vessels. The trypan blue absorption test demonstrated that postnatal PLS possessed an absorptive function and had transformed to mature lymphatic stomata (MLS) by PND 1. Thus, NLS were renamed of MLS. At PND 5, the cuboidal mesothelial cell ridge (CMCR) appeared with increased CMC areas. At PND 10, CMCR were fused to form the band-like CMC area with much more MLS distributed in the muscular portion of the diaphragm. With distribution area and density of PLS increasing and growth of lymphatic vessels, an increased absorptive function from the peritoneal cavity was observed in the experiment.     

Endothelin-1 and endothelial nitric oxide synthase immunoreactivity in lymphatic vessels of the uterine broad ligament during the estrous cycle in the pig

Immunohistochemical localization and distribution of endothelin (ET-1) and nitric oxide synthase (eNOS) were investigated in precollector and collector lymphangions of lymphatic vessels leaving the ovary and were found in the vascular subovarian plexus (mesovarium) as well as in those emanating from the oviductal isthmus and uterine horn (mesosalpinx and mesometrium, respectively) forming the paraovarian lymphatic plexus in the broad ligament of the uterus during different phases of the estrous cycle in pigs. The polyclonal antibody for ET-1 and the monoclonal antibody for eNOS isoform were used for studies on the light-microscopic level. Immunoreactivities to both ET-1 and eNOS were observed in the endothelial cell cytoplasm of precollector and collector lymphangions and were not demonstrated in smooth muscle cells of the lymphatics examined. In the endothelium, the intensity of immunostaining for ET-1 and eNOS was found to be estrous phase-dependent and differed between precollector and collector lymphangions. In general, immunoreactivity to ET-1 was more intense in the endothelium of shrunken lymphangions, whereas that for eNOS was more intense in lymphangions with the large lumen. These results suggest that ET-1 and eNOS can play a role in mechanisms regulating the vascular contractile activity promoting lymph flow during the estrous cycle in the porcine broad ligament.     

Development of the lymphatic network in the muscle coat of the rat jejunum as revealed by enzyme-histochemistry

The process of lymphangiogenesis was studied in the muscle coat of the rat small intestine by light and scanning and transmission electron microscopy; identification of lymphatic vessels was made by 5'-nucleotidase staining. Light and scanning electron microscopy demonstrated that the intramuscular lymphatic network formation, which started only postnatally, was attributable to the vascular sprouting of slender lymphatic endothelial projections and to a splitting of the vessels, causing intervascular meshes of various sizes. The growing lymphatics were consistently closed by the endothelial cells, which were characterized by an abundance of cell organelles and prominent cytoplasmic processes. The cells often revealed close contacts with the processes of developing smooth muscle cells in the jejunal muscle coat, suggesting a possible role for the latter cells in the guidance of the lymphatic extension. The present study is the first to suggest the closed nature of lymphatics persisting throughout their development, even at the initial stage of lymphangiogenesis.     

Development of lymphatic vessels in mouse embryonic and early postnatal hearts

We aimed to study the spatiotemporal pattern of lymphatic system formation in the embryonic and early postnatal mouse hearts. The first sign of the development of lymphatics are Lyve-1-positive cells located on the subepicardial area. Strands of Lyve-1-positive cells occur first along the atrioventricular sulcus of the diaphragmatic surface and then along the great arteries. Lumenized tubules appear, arranged in rows or in a lattice. They are more conspicuous in dorsal atrioventricular junction, along the major venous and coronary artery branches and at the base of the aorta and the pulmonary trunk extending toward the heart apex. At later stages, some segments of the lymphatic vessels are partially surrounded by smooth muscle cells. Possible mechanisms of lymphangiogenesis are: addition of Lyve-1-positive cells to the existing tubules, elongation of the lymphatic lattice, sprouting and coalescence of tubules. We discuss the existence of various subpopulations of endothelial cells among the Lyve-1-positive cells.     

The beta-chemokine receptor D6 is expressed by lymphatic endothelium and a subset of vascular tumors

The lymphatic vessels (lymphatics) play an important role in channeling fluid and leukocytes from the tissues to the secondary lymphoid organs. In addition to driving leukocyte egress from blood, chemokines have been suggested to contribute to leukocyte recirculation via the lymphatics. Previously, we have demonstrated that binding sites for several pro-inflammatory beta-chemokines are found on the endothelial cells (ECs) of lymphatics in human dermis. Here, using the MIP-1alpha isoform MIP-1alphaP, we have extended these studies to further support the contention that the in situ chemokine binding to afferent lymphatics exhibits specificity akin to that observed in vitro with the promiscuous beta-chemokine receptor D6. We have generated monoclonal antibodies to human D6 and showed D6 immunoreactivity on the ECs lining afferent lymphatics, confirmed as such by staining serial skin sections with antibodies against podoplanin, a known lymphatic EC marker. In parallel, in situ hybridization on skin with antisense D6 probes demonstrated the expression of D6 mRNA by lymphatic ECs. D6-immunoreactive lymphatics were also abundant in mucosa and submucosa of small and large intestine and appendix, but not observed in several other organs tested. In lymph nodes, D6 immunoreactivity was present on the afferent lymphatics and also in subcapsular and medullary sinuses. Tonsilar lymphatic sinuses were also D6-positive. Peripheral blood cells and the ECs of blood vessels and high endothelial venules were consistently nonreactive with anti-D6 antibodies. Additionally, we have demonstrated that D6 immunoreactivity is detectable in some malignant vascular tumors suggesting they may be derived from, or phenotypically similar to, lymphatic ECs. This is the first demonstration of chemokine receptor expression by lymphatic ECs, and suggests that D6 may influence the chemokine-driven recirculation of leukocytes through the lymphatics and modify the putative chemokine effects on the development and growth of vascular tumors.     

Intrinsic interrelation of lymphatic endothelia with nerve elements in the monkey urinary bladder

Histochemical staining techniques for 5'-nucleotidase (5'-Nase) and acetylcholinesterase (AChE) were undertaken to localize the lymphatic network and nerve plexus in the monkey urinary bladder. Abundant 5'-Nase-positive lymphatic networks were characterized by increased number of valve-like structures and decreased calibre of blind-ends from the subepithelium to the subserosa. AChE-positive nerve fibers were visible throughout the vesical walls as fine plexuses, the densest being the neuromuscular plexus among the detrusor muscle cells or in each muscle bundle. AChE-positive nerve fibers or terminals were more frequently discernible around blood vessels than around lymphatics, and showed more intimate association with the lymphatics in the muscularis than those in the subepithelium. The nerve terminals in the subepithelium were frequently separated from attenuated lymphatic endothelium by the long processes of fibroblasts or some connective tissue cells. An ultrastructural observation revealed that unmyelinated nerve fibers with numerous neurofilaments and neurotubules run in close apposition to the lymphatic endothelium. Noteworthily, fewer terminal varicosities containing numerous small agranular vesicles (30-50 nm) and mitochondria, partially or completely bare of their Schwann cell covering in the vicinity of the lymphatic endothelium, were found in the subendothelium of initial lymphatics than in collecting ones. These terminals were occasionally identified at a distance of 120-350 nm from the subendothelial aspect of valve-originating roots, although no direct innervation of the vascular muscle cells could be found. A loose fibro-elastic connective tissue was usually interlaced between glial cell covering and lymphatic endothelium. The intrinsic interrelation of the lymphatic wall with the nerve plexus implies that the twisted subendothelial nerve terminals might be involved in intramural lymph drainage of the bladder.     

Production of two novel monoclonal antibodies that distinguish mouse lymphatic and blood vascular endothelial cells

We produced two novel rat monoclonal antibodies (LA102 and LA5) to identify mouse lymphatic vessels and blood vessels, respectively. We characterized the two antibodies as to the morphological and functional specificities of endothelial cells of both types of vessels. The antibodies were produced by a rapid differential immunization of DA rats with collagenase- and neuraminidase-treated mouse lymphangioma tissues. LA102 specifically reacted with mouse lymphatic vessels except the thoracic duct and the marginal sinus of lymph nodes, but not with any blood vessels. In contrast, LA5 reacted with most mouse blood vessels with a few exceptions, but not with lymphatics. LA102 recognized a protein of 25–27 kDa, whereas LA5 recognized a molecule of 12–13 kDa. Neither antibody recognized any currently identified lymphatic or vascular endothelial cell antigens. Immunoelectron microscopy revealed that the antigens recognized by LA102 and LA5 were localized on both luminal and abluminal endothelial cell membranes of each vessel type. Interestingly, LA102 immunoreactivity was strongly expressed on pinocytic or transport vesicle membrane in the cytoplasm of lymphatic endothelium. Besides endothelial cells, both antibodies also recognized some types of lymphoid cells. Since, the LA102 antigen molecule is expressed on some lymphoid cells, it may play important roles in the migration of lymphoid cells and in some transport mechanisms through lymphatic endothelial cells.     

Plasticity of button-like junctions in the endothelium of airway lymphatics in development and inflammation

Endothelial cells of initial lymphatics have discontinuous button-like junctions (buttons), unlike continuous zipper-like junctions (zippers) of collecting lymphatics and blood vessels. Buttons are thought to act as primary valves for fluid and cell entry into lymphatics. To learn when and how buttons form during development and whether they change in disease, we examined the appearance of buttons in mouse embryos and their plasticity in sustained inflammation. We found that endothelial cells of lymph sacs at embryonic day (E)12.5 and tracheal lymphatics at E16.5 were joined by zippers, not buttons. However, zippers in initial lymphatics decreased rapidly just before birth, as buttons appeared. The proportion of buttons increased from only 6% at E17.5 and 12% at E18.5 to 35% at birth, 50% at postnatal day (P)7, 90% at P28, and 100% at P70. In inflammation, zippers replaced buttons in airway lymphatics at 14 and 28 days after Mycoplasma pulmonis infection of the respiratory tract. The change in lymphatic junctions was reversed by dexamethasone but not by inhibition of vascular endothelial growth factor receptor-3 signaling by antibody mF4-31C1. Dexamethasone also promoted button formation during early postnatal development through a direct effect involving glucocorticoid receptor phosphorylation in lymphatic endothelial cells. These findings demonstrate the plasticity of intercellular junctions in lymphatics during development and inflammation and show that button formation can be promoted by glucocorticoid receptor signaling in lymphatic endothelial cells.     

Microlymphatics and lymph flow

A careful review of several different organs shows that with the information available today the beginnings of the microlymphatics in the tissue consist of endothelialized tubes only. Lymphatic smooth muscle within the collecting lymphatics appears further downstream, in some organs only outside the parenchyma. This particular anatomic picture has been observed in many different mammalian organs and in humans. The nonmuscular, so-called initial, lymphatics are the site of interstitial fluid absorption that requires only small and transient pressure gradients from the interstitium into the initial lymphatics. A fundamental question concerns the mechanism that causes expansion and compression of the initial lymphatics. I presented several realistic proposals based on information currently on hand relevant to the tissue surrounding the initial lymphatics. To achieve a continuous lymphatic output, periodic (time variant) tissue stresses need to be applied. They include arterial pressure pulsations; arteriolar vasomotion; intestinal smooth muscle contractions and motilities; skeletal muscle contraction; skin tension; and external compression, such as during walking, running, or massage, respiration, bronchiole constriction, periodic tension in tendon, contraction and relaxation of the diaphragm, tension in the pleural space during respiration, and contractions of the heart. The nonmuscular initial lymphatic system drains into a set of contractile collecting lymphatics, which by way of intrinsic smooth muscle propel lymph fluid. The exact transition between noncontractile and contractile lymphatics has been established only in a limited number of organs and requires further exploration. Retrograde flow of lymph fluid is prevented by valves. There are the usual macroscopic bileaflet valves in the initial and collecting lymphatics and also microscopic lymphatic endothelial valves on the wall of the initial lymphatics. The latter appear to prevent convective reflow into the interstitium during lymphatic compression. Many of the lymph pump mechanisms have been proposed in the past, and most authors agree that these mechanisms influence lymph flow. However, the decisive experiments have not been carried out to establish to what degree these mechanisms are sufficient to explain lymph flow rates in vivo. Because individual organs have different extrinsic pumps at the level of the initial lymphatics, future experiments need to be designed such that each pump mechanism is examined individually so as to make it possible to evaluate the additive effect on the resultant whole organ lymph flow.(ABSTRACT TRUNCATED AT 400 WORDS)     

家兔回肠淋巴管三维结构的扫描电镜观察

目的　探讨回肠淋巴管的三维结构及流注关系。方法　将Mercox注入家兔回肠壁内制成淋巴管铸型 ,在扫描电镜下观察回肠各层淋巴管的三维结构。结果　回肠的粘膜层、粘膜下层、肌层和浆膜层都有毛细淋巴管网及淋巴管。在小肠绒毛内存有中央乳糜管 ,铸型样品上可见其立体结构 ,可见中央乳糜管注入粘膜层和粘膜下层的毛细淋巴管网 ,该网汇合而成的淋巴管穿过肌层进入浆膜层 ,之后以淋巴集合管的形式入肠系膜淋巴管而离开回肠。铸型标本可见淋巴管呈串珠状外观 ,管壁表面有双凹切迹 ,相当于淋巴管瓣膜的部位。铸型表面还可见淋巴管内皮细胞的椭圆形压迹 ,光镜下可见粘膜下与肌层之间存有三角形间隔 ,其内动脉与两条淋巴管并行。结论　中央乳糜管注入粘膜下毛细淋巴管网 ,该网与粘膜下淋巴管网相连 ,此淋巴管再穿肌层入浆膜层后离开回肠 ,并见淋巴通道存在于中央糜管周围。     

Lymphatic vessels of the mammalian heart

An in situ heart lung preparation was developed to label lymphatics of the actively beating dog heart with subsequent fixation by vascular perfusion. Immediately after interstitial injections of trypan blue and colloidal carbon, a rich plexus of lymphatic vessels was visualized in the epicardium of the actively beating heart. With this method of fixation, tissue preservation is generally excellent and uniform throughout the heart. In thin sections examined with the electron microscope, lymphatic vessels are easily recognized by the content of plasma proteins which is preserved as an electron dense precipitate that is evenly dispersed throughout the lumen. An extensive plexus of thin walled lymphatic vessels is observed throughout the epicardial, myocardial and subendocardial regions. Numerous anchoring filaments are observed closely apposed to the abluminal endothelial surface which extend into the surrounding connective tissue. The distribution and ultrastructure of the cardiac lymphatic vessels are discussed in relation to their role in the removal of interstitial fluid from the heart.     

Lymphatic differentiation in renal angiomyolipomas

Renal angiomyolipomas are mesenchymal neoplasms with varying proportions of smooth muscle, adipose tissue, and abnormal blood vessels. Although the presence of lymphangiomatous-like foci is frequently noted in large series of angiomyolipoma, lymphatic differentiation has not been previously studied. Twelve angiomyolipomas from 10 patients were identified. All tumors expressed a melanocytic marker, HMB-45 or Melan-A. Twenty-eight paraffin blocks (1-4 per tumor) were stained for lymphatic endothelial cell markers, podoplanin, and D2-40, and the presence and distribution of lymphatic differentiation were recorded. The angiomyolipomas ranged from typical triphasic tumors to leiomyoma-like and lipoma-like tumors. All 12 tumors showed positive staining with podoplanin, and all 6 tumors stained for D2-40 were also positive, indicative of lymphatic differentiation. Lymphatic differentiation was variably observed throughout the tumors. It was most prevalent in myoid areas of the triphasic angiomyolipomas and in the leiomyoma-like variant, but infrequent and widely scattered within the adipose regions of triphasic angiomyolipoma and in the lipoma-like variant. The lymphatics were usually small, often irregularly shaped, and isolated vessels in fat, whereas in myoid regions lymphatics were clustered and in some areas formed a sinusoidal or labyrinth-like pattern. Lymphatics were commonly adjacent to abnormal arteries. However, unlike the lymphatics in the normal renal cortex, a consistent adventitial association was not observed and the clustering around arteries is regarded as reflecting the myoid regions that typically exist in these areas. In conclusion, lymphatic differentiation is common in angiomyolipomas, preferentially located in myoid regions. These data expand the mesenchymal pluripotential profile of renal angiomyolipomas.     

Structure and distribution of the lymphatic vessels in the parietal pleura of the monkey as studied by enzyme-histochemistry and by light and electron microscopy.

The entire distribution of lymphatics in whole mount preparations of the Japanese monkey was studied using the enzyme-histochemical technique reported by KATO et al. (1990, 1991). In this staining, the lymphatic endothelium was colored dark brown by its positive 5'-nucleotidase activity, while most blood vessels (especially arterioles) were colored blue due to their positive alkaline phosphatase reaction. The whole mount preparations of the pleura treated enzyme-histochemically clearly indicated the distribution, branching patterns and running courses of lymphatic vessels. They revealed numerous short blind-ending knobs which represented the initial portions of lymphatics. These knobs were seen near the surface of the parietal pleura along its entire extent. In the costal and diaphragmatic pleura, the lymphatics ran parallel to the intercostal muscle fibers, but perpendicular to the tendinous and muscular fibers of the diaphragm; they formed ladders, independent of the courses of blood vessels. In the mediastinal pleura, lymphatic vessels showed a tree-like branching accompanying blood vessels. Under the light microscope, toluidine-blue stained semithin sections revealed the initial part of lymphatics as a small irregularly outlined cavity (7-10 microns in diameter) surrounded by a dense connective tissue. This lymphatic dilation was sometimes located close to a thin mesothelial layer. Such a structure suggesting a "stoma" was seen near the attachment of the muscular diaphragm to the sternum and along the borders of the ribs. Transmission electron microscopy revealed an occasional interruption in the mesothelium. This stoma continued to a submesothelial cavity whose base comprised an attenuated endothelium of an extended lymphatic vessel.     

结肠的器官内淋巴管

本文对家兔、大白鼠和豚鼠的结肠器官内淋巴管进行了光镜和电镜观察。结肠粘膜层毛细淋巴管位于肠腺底与粘膜肌之间。粘膜下层毛细淋巴管位于粘膜肌直下方;淋巴管多位子其深方。肌层和浆膜层存有毛细淋巴管和淋巴管。毛细淋巴管内皮细胞质中有大量的囊泡,囊泡与细胞质膜有密切关系,淋巴管内皮细胞间的连接主要有三种形式,即重叠连接、指状插入连接和端端连接。淋巴管壁存有内皮内管道。     

家兔空肠淋巴管铸型的扫描电镜观察

为了探究空肠各层淋巴管的三维结构，将Ｍｅｒｃｏｘ注入家兔空肠壁内，制成淋巴管铸型后，在扫描电镜下观察。同时做半薄切片，以配合观察铸型标本。在空肠的粘膜层、粘膜下层、肌层等都存有毛细淋巴管、淋巴管。在小肠绒毛内可见到中央乳糜管，其三维结构在铸型标本上显示非常清楚；该管注入粘膜层和粘膜下层的毛细淋巴管网，从网发出淋巴管穿肌层，入浆膜层，离开空肠。还可见到淋巴管铸型呈串珠状外观；铸型表面存有双凹切迹，此处相当于瓣膜的部位。铸型表面还呈现出淋巴管内皮细胞核的压迹     

Light and electron microscope observations of the lymphatic drainage units of the peritoneal cavity of rodents

Fluid, particles, and cells are taken up from the peritoneal cavity by lymphatic drainage units, which, in the mouse and rat, are located along the peritoneal surface of the muscular portion of the diaphragm. The drainage units are composed of three specifically differentiated components: a lymphatic lacuna, a covering of lacunar mesothelium, and intervening submesothelial connective tissue. The units are drained by connecting lymphatic vessels that cross the diaphragm to empty into collecting lymphatic vessels running along the pleural surface of the diaphragm. The collecting lymphatics empty into parasternal lymphatic trunks. In this report, we briefly review critical features of the drainage apparatus and describe new observations, summarized below, about their structure. Around the rim of stomata, the mesothelial openings that lead into the lymphatic lacunae, plasma membranes of lacunar mesothelial cells and of lacunar enidothelial cells abut but are not linked to one another by recognizable junctional specializations. Lacunarendothelial cells often extend valve-like processes that bridge the distal end of the channel beneath the stoma. The configuration of the endothelial processes may be complex. Occasionally, processes from fibroblasts in the submesothelial connective tissue adjacent to stomata make contact with the interstitial surface of lacunar endothelial cells. A discontinuous elastic layer in the submesothelial connective tissue spans the roof of each lacuna. Connecting and collecting lymphatics, which drain lymphatic lacunae, possess endothelial valves. Possible functions for each of these newly described structural features are discussed.     

Lymphatic capillaries of the pig lung: TEM and SEM observations

Pulmonary lymphatic vessels extend within the connective tissue sheets surrounding airways and blood vessels. Frequently in this location they also border the lobular parenchyma, but no lymphatic vessels have been found within intralobular compartments between blood capillaries and alveoli. The presence and distribution of lymphatic vessels in pulmonary tissue are consistent with an important role for the lymphatic system in the clearance of interstitial fluids in the lung. Pulmonary lymphatic channels have structural characteristics of initial lymphatics; their walls are formed only by an endothelial layer, and no muscular cells are present. A network of anchoring filaments and collagen and elastic fibers surrounds the vessel walls. Because the lung is a mobile organ the tissue undergoes compression and distension during respiratory phase. These modifications could have a role in the mechanisms for lymph formation and flow. © 1994 Wiley-Liss, Inc.     

Cytoarchitecture of the lamina muscularis mucosae and distribution of the lymphatic vessels in the human stomach

The aim of the present study was to clarify the anatomical structure of the lamina muscularis mucosae (LMM) in the human stomach and to correlate it with the lymphatic spread of gastric cancer cells. Human stomachs taken at operation or autopsy were used. The specimens derived from these stomachs were examined by light microscopy immunohistochemistry and scanning electron microscopy (SEM). In the cardia and pyloric wall, bundles of smooth muscle cells of the LMM were relatively loose and thin and formed a reticular configuration. Small lymphatic capillaries (approximately 10–30 μm in diameter) were present directly above the LMM, and relatively large lymphatics (approximately 80–100 μm in diameter) were observed in the submucosal layer and within the LMM. In contrast, the LMM in the fundus, body, and antral wall was composed of tight, thick bundles of smooth muscle cells that ran straight. Large lymphatics were found directly beneath the LMM, but they were few in the lamina propria mucosae. In addition, lymphatics adjacent to veins were also found in the submucosa of the fundus. Structural differences in the LMM of the stomach wall might depend on physiological function. In this study, the relationship between the cytoarchitecture of the LMM or the distribution of lymphatic vessels and cancer invasion is discussed.     

回肠淋巴管三维结构的扫描电镜观察

目的:探讨回肠淋巴管的三维结构及流注关系;方法:使用16只家免,将Mercox注入动物回肠壁内,制成淋巴管铸型后,在扫描电镜下观察了回肠各层淋巴管的三维结构。为配合铸型标本,同时制作了半薄切片;结果:通过对回肠淋巴管的二维及三维结构的观察,可见回肠的粘膜层、粘膜下层、肌层和浆膜层都有毛细淋巴管网及淋巴管。在小肠绒毛内存有中央乳糜管,铸型样品上可见其立体结构。又观察到中央乳糜管注入粘膜层和粘膜下层的毛细淋巴管网。该网汇合而成的淋巴管穿过肌层,进入浆膜层,之后以淋巴集合管的形式入肠系膜淋巴管而离开回肠。铸型标本可见淋巴管呈串珠状外观,管壁表面有双凹切迹,此相当于淋巴管瓣膜的部位。铸型表面还可见淋巴管内皮细胞的椭圆形压迹。光镜下可见粘膜下与肌层之间存有三角形间隔,其内动脉与两条淋巴管并行;结论:中央乳糜管注入粘膜下毛细淋巴管网,该网与粘膜下淋巴管网相连。此淋巴管再穿肌层入浆膜层后离开回肠。本文见到淋巴通道存于中央乳糜管周围。淋巴液的形成、运输与淋巴管周围的动脉搏动有关。