Blood supply to the lymphatic vessels in the leg: An incidental finding

There are no reports or images of the blood supply to the lymphatic vessels. One lower limb of an unembalmed human cadaver was studied. Hydrogen peroxide (6%) was applied to find the lymphatic vessels by using a surgical microscope. The vessels were injected with a radio‐opaque mixture and dissected. During the dissection, several sites of paralymphatics arteriole nutrient (PAN) vessels were found in close proximity to collecting lymphatic vessels in the medial aspect of the leg. The caliber of the lymphatic vessels was about 1 mm. The caliber of PAN vessels was <0.1 mm. The blood vessels were seen running along the lymphatic vessels. Some of them crossing the lymphatics and supplying the fatty tissue nearby and some running parallel on the lymph vessel walls. Histology sections show different‐sized PAN vessels containing blood cells situated close to the lymphatic wall and within the lymphatic vessel wall. PAN vessels have been found and described. It will upgrade our anatomical knowledge and also be of benefit for medical and/or scientific research. Clin. Anat. 23:451–454, 2010. © 2010 Wiley‐Liss, Inc.     

Pulmonary lymphatic filling is increased in spontaneously hypertensive rats

Extravascular lung liquid must rely on tissue-space pressure gradients to drive it into the lymphatics because the fluid is outside the lymphatic contractile pumping and valve control. Focal tissue pressure changes could result from muscular contraction in the blood vessel walls. Perivascular lymphatics usually lie within the adventitia of pulmonary blood vessels, and are generally more noticeable in veins than arteries. Spontaneously hypertensive rats have exaggerated focal pulmonary venous muscle (venous sphincters). These muscular tufts are often near initial lymphatics; if their contraction was important for lymph transport, spontaneously hypertensive rats could have more lymphatic filling in the areas of the pulmonary venous sphincters than normotensive rats. Because the focal muscularity is found in pulmonary veins more than arteries, veins may have more focal lymphatic filling than arteries. To test these hypotheses, lung histology and vascular and lymphatic casts of spontaneously hypertensive and normotensive rats were examined. Contracted venous sphincters were found on 108 of 127 veins with lymphatics in the spontaneously hypertensive rats and 5 of 41 in the normotensive rats P<0.01). The spontaneously hypertensive rats had deeper venous contractions and more lymphatic filling around both arteries and veins (P<0.01). In the hypertensive rats, the venous was greater than the arterial lymphatic filling (P<0.01). On the pleural surface, hypertensive rats also had greater lymphatic filling than controls (P<0.01). This anatomic evidence suggests that pulmonary venous sphincters are associated with focal lymphatic filling, and perivascular muscle action might be a component of the pulmonary lymphatic system.     

Lymphatic involvement in the histopathogenesis of mucous retention cyst

Mucous retention cyst results from extravasation of saliva. Our intent was to study the role of lymphatics in its pathogenesis. Twenty-three surgical specimens of mucous retention cyst of the lip were examined for involvement of lymphatic vessels by a comparative immunohistochemical demonstration of lymphatic and blood vascular endothelial cells, as well as lymphatic and salivary contents. Mucous retention cysts were histopathologically classified into three stages: early, intermediate, and advanced. In the early stage, there was diffuse extravasation of mucous material in the interstitium of the lamina propria or the submucosal layer of the oral mucosa. In the intermediate stage, lymphatics, which were clearly revealed and immunohistochemically distinguished from blood vessels by monoclonal antibody D2-40, were dilated and finally ruptured, leaving fragments of lymphatic walls in the periphery of mucous pools. In the advanced stage, thick cyst walls of granulation tissue were formed around mucous retention. Lymphatics were no longer involved in the granulation tissue wall, which was actively driven by blood vessel formation. The results suggest that the lymphatic rupture seems to contribute to the enlargement in the pathogenesis of mucous retention cyst.     

A Light Microscopical, Immunohistochemical, and Ultrastructural Comparison of Hemangiomata and Lymphangiomata

In this study we have compared the light microscopical, immunohistochemical, and ultrastructural features of five hemangiomata of the dermis with five lymphangiomata of the dermis and subcutaneous tissue. We have attempted to define differentiating features with regard to the ultrastructural appearances and the immunohistochemical staining for the endothelial markers factor VIII-related antigen (FVIII:RAg) and Ulex europaeus agglutinin I (UEA-I). In addition, immunolocalization of FVIII:RAg at the ultrastructural level was performed to compare its distribution within endothelial cells of neoplastic blood vessels and lymphatic vessels.

The results show that immunohistochemical staining for FVIII:RAg and UEA-I does not differentiate between blood and lymphatic vessels. However, the presence of a fragmented basal lamina and anchoring filaments does distinguish lymphatic vessels from blood vessels ultrastructurally.     

Distribution of lymphatic vessels in mammary glands of ewes

Six multiparous ewes, three of which were lactating and the remaining three in an advanced stage of mammary involution, were used to study the distribution of lymphatic vessels in the mammary gland. The lymphatic system was distended by ligation of the regional efferent lymphatic ducts and either reconstituted blood or Latex was used to fill the blood vascular system. After fixation, distribution of lymphatic vessels was studied macroscopically and microscopically. One to three mammary nodes were situated at the postero-dorsal aspect of each gland. Entering and leaving the nodes were 8 to 12 major afferent and 2 to 4 efferent ducts. Four or five of the afferent ducts accompanied the external pudendal artery and vein and their radicles emerged from the deep parenchyma of the gland. The remaining afferent ducts emerged from the parenchyma of the gland independent of blood vessels and their radicles drained both superficial and deep parenchyma. Lymphatic vessels were found in the connective tissue between lobes, within lobes and between lobules. Lymphatic capillaries were observed in the connective tissue within lobules and also in areas adjacent to the alveolar epithelium. Lymphatic vessels in the connective tissue between lobes and the larger vessels were supplied with valves and their walls posessed an endothelial cell lining together with smooth muscle and connective tissue layers. Finer lymphatic vessels appeared to consist of only a simple endothelial cell lining and valves were not found.     

Histochemical analysis of lymphatic endothelial cells in the pancreas of non-obese diabetic mice

We studied the relationship between insulitic development and function-structural changes of pancreatic lymphatics in non-obese diabetic (NOD) mice using combined 5'-nucleotidase (5'-Nase) enzyme histochemical and secondary lymphoid tissue chemokine (SLC/CCL21) immunohistochemical methods. Interlobular lymphatic vessels were positive for 5'-Nase throughout the pancreas, and dependent on both blood vessels and pancreatic ducts. Intralobular initial lymphatics were rare and occasionally ran in the neighbourhood of islets. During the non-insulitic stage, the 5'-Nase-reactive product was evenly distributed on the surface of lymphatic endothelial cells (LECs) with weak expression of CCL21. The activity of 5'-Nase on lymphatic vessels became slightly reduced as insulitis developed. The increasing blood glucose values appeared to be consistent with an increasing CCL21 expression by the endothelial lining, especially on the surface of LECs adjacent to the infiltrated islets and tissues. Lymphocytes and dendritic cells (DCs) were frequently located in the connective tissue, surrounding the lymphatic wall with deposition of 5'-Nase precipitates. As the infiltration became severe, lymphocytes and DCs accumulated within lymphatic vessels and expressed high levels of CCL21. The most significant finding was that many DCs adhered to lymphatic vessels, transmigrating via the thin and indented endothelial walls. The activity of 5'-Nase was increased on the adhesion surface between DCs (or lymphocytes) and LECs. The latter were characterized by open intercellular junctions and obvious cytoplasmic protrusions. These results suggest that LECs closely interact with DCs and lymphocytes, and play a key role in the migration of DCs and lymphocytes via lymphatic vessels during the pathological processes of insulitis in NOD mice.     

家兔肺内淋巴管的微细分布

目的：研究家兔肺内淋巴管的微细分布,探讨肺泡隔内是否存在淋巴管。方法：采用5′-核苷酸酶-碱性磷酸酶双重染色法(5′-Nase-ALP)、半薄切片光镜观察、超薄切片电镜观察。结果：(1)肺内淋巴管存在于富含结缔组织区,延伸至呼吸性细支气管区,不延伸至肺泡区,呼吸性细支气管外膜下可见毛细淋巴管,肺泡隔内未见毛细淋巴管和淋巴管,仅见到大量呈蓝色的毛细血管。(2)伴行肺动脉的淋巴管为肺深淋巴管系的主流,其末梢向小叶中央延伸到末级微动脉附近。(3)伴行肺静脉的淋巴管位于静脉外膜边缘的结缔组织中,与肺泡紧密相邻。结论：肺泡隔内无淋巴管,肺内淋巴管起始于呼吸性支气管。     

Lymph circulation: physiology, pharmacology, and biomechanics

Lymph is the fluid in the lymphatic system. The lymphatic system, a complex network of vessels, is essentially a drainage system within the body which transports excess fluid and metabolic waste products from interstitial spaces into the blood circulatory system. Lymph flow is governed by extrinsic forces due to the movements of organs and skeletal muscles which exert external pressure on the lymphatic walls, and by the intrinsic forces due to rhythmic contractions of smooth muscle in the walls of the lymphatic vessels which play a major role in lymph circulation. Intensities of these lymphatic smooth-muscle contractions are modulated by several humoral mediators such as epinephrine, serotonin, and PGE1. These notions of lymphology, together with principles of mechanics, have been integrated into mathematical models of lymph circulation. Model analysis has revealed several interesting features of lymph circulation and lymphatic system design. Distention-induced enhancement of contractility is important in achieving significant increase in lymph flow during edema.     

Morphometric analysis of intralobular, interlobular and pleural lymphatics in normal human lung

In spite of their presumed relevance in maintaining interalveolar septal fluid homeostasis, the knowledge of the anatomy of human lung lymphatics is still incomplete. The recent discovery of reliable markers specific for lymphatic endothelium has led to the observation that, contrary to previous assumptions, human lymphatic vessels extend deep inside the pulmonary lobule in association with bronchioles, intralobular arterioles or small pulmonary veins. The aim of this study was to provide a morphometric characterization of lymphatic vessels in the periphery of the human lung. Human lung sections were immunolabelled with the lymphatic marker D2-40, followed by blood vessel staining with von Willebrand Factor. Lymphatic vessels were classified into: intralobular (including those associated with bronchovascular bundles, perivascular, peribronchiolar and interalveolar), pleural (in the connective tissue of the visceral pleura), and interlobular (in interlobular septa). The percentage area occupied by the lymphatic lumen was much greater in the interlobular septa and in the subpleural space than in the lobule. Most of the intralobular lymphatic vessels were in close contact with a blood vessel, either alone or within a bronchovascular bundle, whereas 7% were associated with a bronchiole and < 1% were not connected to blood vessels or bronchioles (interalveolar). Intralobular lymphatic size progressively decreased from bronchovascular through to peribronchiolar, perivascular and interalveolar lymphatics. Lymphatics associated with bronchovascular bundles had similar morphometric characteristics to pleural and interlobular lymphatics. Shape factors were similar across lymphatic populations, except that peribronchiolar lymphatics had a marginally increased roundness and circularity, suggesting a more regular shape due to increased filling, and interlobular lymphatics had greater elongation, due to a greater proportion of conducting lymphatics cut longitudinally. Unsupervised cluster analysis confirmed a marked heterogeneity of lymphatic vessels both within and between groups, with a cluster of smaller vessels specifically represented in perivascular and interalveolar lymphatics within the alveolar interstitium. Our data indicate that intralobular lymphatics are a heterogeneous population, including vessels surrounding the bronchovascular bundle analogous to the conducting vessels present in the pleural and interlobular septa, many small perivascular lymphatics responsible for maintaining fluid balance in the alveolar interstitium, and a minority of intermediate lymphatics draining the peripheral airways. These lymphatic populations could be differentially involved in the pathogenesis of diseases preferentially involving distinct lung compartments.     

The ultrastructure of lymphatic valves in rabbits and mice

The ultrastructure of lymphatic valves was studied in rabbits and mice. The lymphatic valves usually consist of two cusps but three or four are sometimes present. The cusps are covered by endothelium. Along the free edge of the cusps are endothelial cells which can differentiate morphologically from other endothelial cells. They are named “tip-cells”; they have pseudopod-like projections and abundant cytoplasmic filaments 60–90 Å in diameter. Vesicles occur in endothelial cells of both lymphatic vessels and their valves; they are on the luminal or connective tissue side and are never provided with a diaphragm like that frequently observed in blood vessels. Joining endothelial cells are zonulae occludentes but desmosomes are not observed. No open intercellular junctions are encountered along the valvular endothelium. A basement membrane (basal lamina) is more frequently observed in valves than in walls of lymphatic vessels. Connective tissue in the cusps consists of collagenous fibrils, fine filaments and fibroblasts.     

Fine structure of the choroidal coat of the avian eye

 To clarify further the functional anatomy of the avian choroid, including its innervation, 12 adult White-Leghorn chickens were studied by standard electron microscopy and immunoelectron microscopy with somatostatin antibody. The endothelial cells of the blood vessels in the choriocapillaris have fenestrations only facing the retina, while the nuclei are situated toward the sclera. In addition to tight junctions and zonulae adherentes, adjoining endothelial cells form gap junctions and dense plaques with attached filaments resembling those of smooth muscle cells. The fine structure of arteries and veins is similar to that of the vasculature described in other organs. The supporting tissue is organized in trabeculae, i.e., bridges of cellular and fibrous elements that surround and sustain blood and lymphatic vessels. This tissue consists primarily of a system of fusiform or star-shaped smooth muscle cells, connected to each other and to those in the vessels’ walls through macular junctions of the adherent type, less prominent than desmosomes, and perhaps also punctiform gap junctions. Occasionally, trabecular smooth muscle cells approach the lymphatic vessels, which lack a muscular tunica, and abut their endothelium with spinous appendages. This stromal muscle tissue may act as a pump for moving the lymph. The suprachoroidea consists of large lymphatic lacunae and the multilayered membrana fusca. The elongated fuscal cells form adherent junctions, tight junctions, and perhaps also gap junctions, suggesting that the membrana fusca exerts complex functions. Nerves containing myelinated axons reach the choroid and divide into smaller branches, a few of which innervate the membrana fusca. Numerous, thin nerve branches reach both the walls of arteries and veins and the trabeculae, and synaptic terminals abut the outer muscular layers of the vessel’s wall and the smooth muscle cells of the supporting tissue. Immunocytochemistry reveals the presence of numerous somatostatin-positive and somatostatin-negative axons and synaptic terminals within both trabeculae and vascular tunica media. The somatostatin-positive axons are presumed to be cholinergic axons of the choroid neurons residing in the ciliary ganglion. Taken together, these observations indicate that the avian choroid is a highly vascularized muscular sheath that may be endowed with degrees of motility and elasticity higher than those of the mammalian choroid and may therefore play an important role in compensation for experimental defocus. Accepted: 21 January 1997     

Lymphangiogenesis in Crohn’s disease: an immunohistochemical study using monoclonal antibody D2-40

Crohn’s disease (CD) is a chronic inflammatory bowel disorder of unknown etiology. An involvement of the intestinal lymphatic system has been suggested. Recently, monoclonal antibodies have become available to distinguish lymphatic vessels from blood vessels. The aim of the study was to examine the distribution of lymphatic vessels in ileal and colic walls of patients affected by CD and compare it with healthy controls and other inflammatory bowel diseases. Twenty-eight cases of CD, 13 cases of other inflammatory bowel diseases, and 10 normal ileal and colic walls were studied. Immunohistochemical staining was performed using the monoclonal antibody D2-40. Quantification of lymphatic vessels was performed by identifying four fields with high density of lymphatics and then counting the number of lymphatic vessels at high resolution. Lymphatic diameter was also evaluated by using an ocular micrometer. Lymphatic vessels showed the highest density in CD specimens. The median number of lymphatics was significantly higher both in ileal and colic samples of CD than the other inflammatory diseases as well as normal controls. Moreover, in patients with CD, diffuse lymphangiectasia was also observed. The present data suggest that lymphangiogenesis and lymphangiectasia probably play a role in the pathogenesis of CD.     

Forms of lung lymphatics: A scanning electron microscopic study of casts

In a recent study, rats given monocrotaline underwent angiogenesis on their pleural surfaces. The rats also had novel structures in their bronchovascular bundles that were detected by scanning electron microscopy of vascular casts. These vessels could have been either new blood capillaries or dilated lymphatic capillaries. To determine if these structures were lymphatics or new blood vessels, specimens from animals that were undergoing angiogenesis were compared to those that were not. Finding similar structures in normal animals would imply that they were lymphatic. The second purpose of this work was to describe the three-dimensional anatomy of the lymphatics of the lung. Cast lymphatics were found in most lungs with edema or angiogenesis, but were rare in other conditions. The vascular structures in question were found in animals not undergoing angiogenesis and were, therefore, lymphatic. Additionally, scanning electron angiogenesis and were, therefore, lymphatic. Additionally, scanning electron microscopy of casts showed several distinct forms of lymphatics in the lung. Prelymphatics are tissues planes beneath the pleura and around bronchovascular structures. They join reservoir, conduit or tubulo-saccular lymphatics. Reservoir lymphatics are broad ribbon-like structures with textured surfaces and small laterally branching pouches. They occur on the pleural surface, are closely linked with prelymphatics, and join conduit lymphatics. Conduit lymphatics are tubular structures that may contain valves, twist and go great distances without accepting tributaries. On the pleural surface, they may wind around blood vessels and vary greatly in diamater. Sacculo-tubular lymphatics surround arteries, veins and bronchioles. They have thin walls with wide saccular segments. They may be so dense that they form cylinders around the vessels or airways. Different forms of lung lymphatics suggest different function and potential. © 1992 Wiley-Liss, Inc.     

Elastin Cables Define the Axial Connective Tissue System in the Murine Lung

The axial connective tissue system is a fiber continuum of the lung that maintains alveolar surface area during changes in lung volume. Although the molecular anatomy of the axial system remains undefined, the fiber continuum of the lung is central to contemporary models of lung micromechanics and alveolar regeneration. To provide a detailed molecular structure of the axial connective tissue system, we examined the extracellular matrix of murine lungs. The lungs were decellularized using a 24 hr detergent treatment protocol. Systematic evaluation of the decellularized lungs demonstrated no residual cellular debris; morphometry demonstrated a mean 39 ± 7% reduction in lung dimensions. Scanning electron microscopy (SEM) demonstrated an intact structural hierarchy within the decellularized lung. Light, fluorescence, and SEM of precision‐cut lung slices demonstrated that alveolar duct structure was defined by a cable line element encased in basement membrane. The cable line element arose in the distal airways, passed through septal tips and inserted into neighboring blood vessels and visceral pleura. The ropelike appearance, collagenase resistance and anti‐elastin immunostaining indicated that the cable was an elastin macromolecule. Our results indicate that the helical line element of the axial connective tissue system is composed of an elastin cable that not only defines the structure of the alveolar duct, but also integrates the axial connective tissue system into visceral pleura and peripheral blood vessels. Anat Rec, 298:1960–1968, 2015. © 2015 Wiley Periodicals, Inc.     

Expression of vascular endothelial growth factor receptor 3 in blood and lymphatic vessels of lung adenocarcinoma

Vascular endothelial growth factor receptor 3 (VEGFR-3) has been proposed as a marker for lymphatic endothelial cells. This study investigated the expression of VEGFR-3 in the tumour vessels of lung adenocarcinoma and evaluated whether VEGFR-3 staining was useful for identifying lymphatic vessels within the tumour stroma. It also explored whether active growth of lymphatic vessels occurred in lung adenocarcinoma. Formalin-fixed, paraffin-embedded specimens obtained from 60 cases of lung adenocarcinoma, including five cases of pure bronchiolo-alveolar carcinoma (BAC) without stromal, vascular, and pleural invasion, were examined. No VEGFR-3-positive vessels were observed in pure BAC, but varying numbers of VEGFR-3-positive vessels were found in 39 of 55 (70.9%) invasive adenocarcinomas. A comparison of serial sections stained for VEGFR-3, CD31, and laminin-1 showed that most of the VEGFR-3-positive vessels appeared to be blood vessels (CD31-positive, laminin-1-positive), but some had the characteristics of lymphatic vessels (variable staining for CD31, little or no staining for laminin-1). VEGFR-3 staining highlighted lymphatic invasion by cancer cells; this invasion could not be detected by CD31 or haematoxylin and eosin (H&E) staining. Active growth of lymphatic vessels (as indicated by nuclear Ki-67 labelling of the endothelium) was observed in five tumours, four of which showed a high level of lymphatic invasion by cancer cells. It was concluded that VEGFR-3 immunostaining did not discriminate clearly between vascular and lymphatic endothelial cells, since expression of VEGFR-3 can be up-regulated in tumour blood vessels. However, VEGFR-3 staining combined with laminin-1 and CD31 staining would be useful for identifying lymphatic vessels and their invasion by tumour cells in a more objective way. Finally, proliferation of lymphatic endothelial cells may occur in association with lymphatic invasion by cancer cells.     

Forms of lung lymphatics: a scanning electron microscopic study of casts.

In a recent study, rats given monocrotaline underwent angiogenesis on their pleural surfaces. The rats also had novel structures in their bronchovascular bundles that were detected by scanning electron microscopy of vascular casts. These vessels could have been either new blood capillaries or dilated lymphatic capillaries. To determine if these structures were lymphatics or new blood vessels, specimens from animals that were undergoing angiogenesis were compared to those that were not. Finding similar structures in normal animals would imply that they were lymphatic. The second purpose of this work was to describe the three-dimensional anatomy of the lymphatics of the lung. Cast lymphatics were found in most lungs with edema or angiogenesis, but were rare in other conditions. The vascular structures in question were found in animals not undergoing angiogenesis and were, therefore, lymphatic. Additionally, scanning electron microscopy of casts showed several distinct forms of lymphatics in the lung. Prelymphatics are tissues planes beneath the pleura and around bronchovascular structures. They join reservoir, conduit or tubulo-saccular lymphatics. Reservoir lymphatics are broad ribbon-like structures with textured surfaces and small laterally branching pouches. They occur on the pleural surface, are closely linked with prelymphatics, and join conduit lymphatics. Conduit lymphatics are tubular structures that may contain valves, twist and go great distances without accepting tributaries. On the pleural surface, they may wind around blood vessels and vary greatly in diameter. Sacculo-tubular lymphatics surround arteries, veins and bronchioles. They have thin walls with wide saccular segments. They may be so dense that they form cylinders around the vessels or airways. Different forms of lung lymphatics suggest different function and potential.     

Lymphatic amyloidosis, a previously unrecognized form of amyloid deposition in generalized amyloidosis

Although amyloid deposition in relation to blood vessels is a well-recognized feature of generalized amyloidosis, lymphatic vessel amyloidosis is not mentioned in the literature. Systematic investigation of tissue removed at autopsy from patients with generalized amyloidosis and biopsy specimens from cases of localized amyloidosis and familial Mediterranean fever showed that amyloid deposition around lymphatics is by no means uncommon. The material investigated was mainly large and small bowel, lung, heart and kidney. Amyloid was identified by green birefringence with the Congo red stain on cross-polarization and lymphatics by their lack of immunostaining for CD34. Involvement of lymphatics was noted in 20 of the 42 organs from which specimens were examined, and was always accompanied by involvement of blood vessels and/or the interstitium. In the intestine, lymphatic amyloidosis was found mainly in the submucosa and subserosa, and was also demonstrated by electronmicroscopy in one case. Although lymphatic amyloidosis was equally common in the heart, lung and kidney, it was usually less prominent here than in the intestine. No lymphatic involvement was seen in localized amyloidosis. As the lymphatics play a central role in the resorption of interstitial proteins, they are probably also involved in the resorption of amyloid proteins. Amyloid deposition in the vicinity of lymphatics is probably the result of decompensation of this process.     

Sensory innervation of the Achilles tendon by group III and IV afferent fibers

Summary In sympathectomized cats the innervation of the Achilles tendon by fine afferent nerve fibers was studied with semithin and ultrathin sections. Several different types of sensory endings of group III and group IV nerve fibers were identified.Of the five different types of endings in the group III range (T III endings), two are located within vessel walls. One of them ends in the circumference of the venous vessels (T III/VV). Its lanceolate terminals have characteristic receptor areas at their edges. The second type ends in the adventitia of lymphatic vessels (T III/LV). Its receptive areas are scattered along their terminal course. Two further group III endings ramify within the connective tissue compartments of the vessel-nerve-fascicles of the peritenonium externum and internum. One type is tightly surrounded by collagen fibrils (T III/PTic); the other terminates between the collagen fiber bundles (T III/PTgc). The latter arrangement recalls the ultrastructural relation between nerve terminals and collagen tissue in Golgi tendon organs.The fifth type innervates the endoneural connective tissue of small nerve fiber bundles (T III/EN). At least some of them come into close contact with bundles of collagen fibers which penetrate the perineural sheath to terminate within the endoneurium.The endings of group IV afferents (T IV endings) show a striking topographic relationship to the blood and lymphatic vessels of all connective tissue compartments of the Achilles tendon. They form penicillate endings which may contain granulated vesicles. In any event, they can easily be discriminated from the T III endings in the vessel walls.In close neighborhood to Remak bundles, a cell has been regularly found which fulfilled all ultrastructural criteria for mast cells. But this cell is not a mast cell proper because it is surrounded by a basal lamina (pseudo mast cell).     

Observation of lymphatic vessels in orbital fat of patients with inflammatory conditions: a form fruste of lymphangiogenesis?

In the absence of antibodies specific for lymphatic vessels, analysis of lymphatic vessels within different tissues has been widely performed with light microscopic and, most importantly, electron microscopic techniques. In regard to lymphatic vessels in the ocular globe and the periocular structures, controversy remains about the specific distribution of lymphatic channels. It is postulated that bulbar and retrobulbar tissues are devoid of lymphatic vessels, but lymphatic vessels have been demonstrated in lacrimal gland and epibulbar conjunctiva. In this study, we analyzed orbital fat for the presence of lymphatic tissue using D2-40, a monoclonal antibody, specific for lymphatic vessels. We found lymphatic vessels present within bulbar conjunctiva extending to the level of the ciliary apparatus. No lymphatics were identified in healthy anterior orbital adipose tissue. In two cases of orbital mucor-mycosis and one case of panendophthalmitis, significant lymphovascular proliferation was present within granulation tissue associated with the acute inflammation. We conclude that lymph vessel proliferation may be induced in inflammatory conditions in tissues which are normally devoid of lymph channels.