Histological, histochemical and immunohistochemical study of the lymph nodes of the one humped camel (Camelus dromedarius)

Prescapular, femoral, mesenteric, mediastinal and splenic lymph nodes from nine camels of one to 12 years of age were studied. There were no obvious structural differences between these different lymph nodes or between the ages. The lymph nodes were surrounded by a capsule formed of two layers, an outer thicker layer of connective tissue and an inner thinner layer mainly of smooth muscles. Trabeculae extended from the inner layer of the capsule dividing the parenchyma characteristically into incomplete lobules. Subcapsular and trabecular lymphatic sinuses were supported by a reticular fiber network. The parenchyma was uniquely different from that of other species, as it was arranged in the form of lymphoid follicles and interfollicular lymphoid tissue. The lymphoid follicles of CD22 positive lymphocytes were supported by a reticular fiber network. This fine network of α-smooth muscle actin positive cells enclosed the lymphoid follicles. The interfollicular tissue was mainly made up of diffusely distributed CD3 positive lymphocytes. MHC class II: DR was expressed by most lymphocytes of the follicles and interfollicular tissue. Lymphatic sinuses and high endothelial venules were found in the interfollicular zone. The lymphatic sinuses were lined by discontinuous endothelial cells. The wall of the high endothelial venules was infiltrated by several lymphocytes and enclosed in a layer of α-smooth muscle actin positive cells. Acid phosphatase positive cells were evenly distributed in the interfollicular zone. A few cells were localized in the lymph follicles. Alkaline phosphatase was observed in the endothelium of the lymphatic sinuses and in the lymphoid follicles.     

The parotid, mandibular and lateral retropharyngeal lymph nodes of the camel (Camelus dromedarius)

The parotid, mandibular and lateral retropharyngeal lymph nodes of the dromedary camel were examined using both light and electron microscopy. All three lymph nodes were lobulated. They did not show the characteristic medulla, cortex and paracortex of typical lymph nodes. Instead, they contained lymphatic nodules, dense anodular lymphoid tissue and diffuse lymphoid tissue dispersed throughout the lymph node. Networks of sinuses were present in the diffuse lymphoid tissue. The diffuse lymphoid tissue in the periphery of all lymph nodes examined was characterized by numerous erythrocytes within and around its network of sinuses. The nodal sinuses were contiguous with the septal vessels, which are considered the possible source of erythrocytes seen in this study. The lymph nodes that were seen in this study resembled the haemolymph nodes of other mammals with regard to their content of erythrocytes but were unique in being located in sites that were typical of ordinary lymph nodes. Morphometric analysis has shown that the percentage volume densities of the stroma and the various parenchymal components were similar in the three lymph nodes.     

Blood vessels of lymph nodes in the pig

Pig lymph nodes have an unusual arrangement of cortical and medullary tissue, and lack a hilus. The aim of the present study was to describe the pathways by which blood reaches these lymph nodes. Natural or synthetic latex casts were made of blood vessels of superficial inguinal, popliteal and jejunal lymph nodes. Major nodal arteries approach these lymph nodes and give rise to about five branches, most of which remain on the node surface. These branches often wrap around part or all of the node in a claw-like manner and they divide to form a network on its surface. Arteries from this network penetrate the capsule directly to supply the lymphoid parenchyma. Anastomoses are common at all levels between the arteries supplying the nodes and arteriovenous anastomoses occur within the nodes. These may help to maintain and regulate blood flow within the lymph node under different conditions of stimulation.     

Extravasation of lymphocytes via paracortical venules in sheep lymph nodes: visualization using an intracellular fluorescent label

In rodents and humans, lymphocytes extravasate into lymph nodes via specialized paracortical venules lined with high endothelium (HEV). Sheep and other ruminants do not have morphologically defined HEV in their lymph nodes. It has been assumed that lymphocyte extravasation in these species proceeds via analogous structures; i.e., paracortical venules lined with low to medium endothelium. In this study, lymphocyte suspensions were prepared from surgically excised lymph nodes of sheep and labeled with an intracellular fluorescent dye, H33342. Labeled cells were infused intravenously back into donors, and sheep were killed at various intervals after infusion. Frozen sections of lymph nodes were examined microscopically for the location of labeled cells. Ten minutes after infusion, labeled cells were seen in the lumen of venules located in the paracortical region of the nodes. At later time points, cells were seen apparently migrating through the venule walls and in the adjacent paracortical tissue. Similar experiments were performed in which H33342-labeled murine lymphocytes were infused into syngeneic mice. When equivalent cell numbers (based on animal size) were infused, no obvious differences were seen between location and kinetics of appearance of labeled cells in lymph nodes of sheep compared to those of mice. These results indicate that lymphocyte extravasation in sheep proceeds via paracortical venules in lymph nodes. The function of these venules appears to be analogous to HEV in nonruminant species.     

Lymph Drainage from the Ovine Tonsils: An Anatomical Study of the Tonsillar Lymph Vessels

Although the tonsils of sheep have gained much attention during the last decade, only few data are available on their lymph vessel architecture. Tonsillar lymph vessels are immunologically important as they form the efferent routes for locally activated immune cells to reach the draining lymph nodes. To gain insight into the tonsillar lymph drainage in the sheep, Indian ink and a casting polymer were injected into the interstitium of the five tonsils present in the heads of slaughtered sheep. This enabled us to determine the draining lymph node and to examine the microscopic organization of lymph vessels using light and scanning electron microscopy. No lymph vessels were observed within the tonsillar lymphoid follicles. The corrosion casts demonstrated that the lymphoid follicles are surrounded by numerous sacculated lymph sinuses that drain into a dense interfollicular lymph vessel network. From here, the lymph flows into single small lymph vessels that in turn drain into larger lymph vessels extending towards the medial retropharyngeal lymph node. The presented results can be valuable for immunological studies, for example during oral or intranasal vaccine development.     

双峰驼血淋巴结的形态结构研究

本研究用解剖学和组织学方法首次确定我国双峰驼具有血淋巴结这一形态结构。其外观呈卵圆形、紫红色，直径6－11mm，常见于皮下结缔组织中。在组织学上，外有一层由胶原纤维、弹性纤维和成纤维细胞构成的薄而疏松的被膜，其中有较多的血管和淋巴管；被膜伸入内部形成细小且分布散乱的小梁，但未将实质分隔成明显的小叶。实质由大量的血窦、较少的淋巴小结和淋巴窦构成，未见索状淋巴组织。血窦可分为边缘窦和中间窦，充满血液，前者位于被膜下方，较宽大，呈索状排列；后者狭窄，吻合成网；窦壁由内皮和基膜组成。淋巴窦较少，窦壁完整，明显扩张。淋巴小结多呈卵圆形，散在分布于血窦之间，由淋巴、网状组织构成，有的有明显的的生发中心。和他种动物相比，双峰驼血淋巴结在组织学上有以下特点：（1）除具有血管和血窦外，还有淋巴管和淋巴窦；（2）实质无皮质和髓质之分；（3）淋巴组织主要为淋巴小结，未见索状的淋巴组织。     

Histology and Ultrastructure of the Lymph Nodes of the Buffalo (Bos bubalus)

Pre‐scapular, femoral and mesenteric lymph nodes from five buffalo calves and five buffalo bulls were studied using light and transmission electron microscopy. The nodes were surrounded with a thin capsule of dense connective tissue and smooth muscles. Subcapsular and trabecular lymphatic sinuses were lined with endothelial cells resting on a basement membrane. The cortex was formed by lymphoid follicles and inter‐follicular lymphocytes. Primary and secondary follicles were observed. The medulla was made up of medullary cords of lymphocytes separated by lymphatic sinuses. These sinuses were lined with a discontinuous epithelium and interestingly crossed by reticular fibres. High endothelial venules were found in the paracortical area. Several lymphocytes were observed infiltrating the wall of these venules. The lymph nodes of the Egyptian water buffalo showed a typical structure compared with the majority of mammals, with no age‐related structural variation.     

Morphology of the lymph nodes in bottlenose dolphin (Tursiops truncatus) and striped dolphin (Stenella coeruleoalba) from the Adriatic Sea

Morphology of the lymph nodes was examined in six bottlenose dolphins (Tursiops truncatus) and three striped dolphins (Stenella coeruleoalba) from the Adriatic Sea. All animals had been found dead in nature. One group of the nodes was taken from the tracheal branching area and was marked as bifurcational lymph node, and the other group was taken from the mesenteric root and was marked as mesenteric lymph node. Microscopic analysis showed that the lymph nodes in both dolphin species were surrounded by a connective tissue capsule comprising smooth muscle cells. The parenchyma of the mesenteric and bifurcational lymph nodes in bottlenose dolphin was divided into the peripherally situated cortex with the lymphatic nodules and diffuse lymphatic tissue, and the centrally situated medulla structured of the medullary cords separated by the medullary sinuses. These lymph nodes structurally correspond to the lymph nodes in the majority of terrestrial mammals. The mesenteric lymph node of striped dolphin also had a peripherally situated cortex and a centrally positioned medulla as the majority of terrestrial mammals. In the bifurcational lymph nodes of striped dolphin, there was a central dense lymphatic tissue with the lymphatic nodules and a peripheral less dense lymphatic tissue structured of the cell cords and sinuses. The bifurcational lymph node in striped dolphin resembled porcine lymph nodes and belonged to the inverse lymph nodes.     

Effect of infections with swine fever virus on immune functions II. Lymphocyte response to mitogens and enumeration of lymphocyte subpopulations

Peripheral blood and spleen lymphocytes from pigs infected with a low-virulent strain of swine fever virus (SFV) were transiently hyporesponsive to the mitogenic action of PHA, PWM and Con A. The mitogenic reactivity of lymphocytes from lymph nodes from such pigs appeared to be enhanced rather than depressed at that time. In addition, hyperresponsiveness of peripheral blood lymphocytes (PBL) to these mitogens occurred in some pigs.PBL from pigs lethally infected with virulent SFV showed a persistent depression of the response to these mitogens, whereas lymphocytes from lymph nodes had a high responding capacity.A lymphocyte response to SFV antigens could not be demonstrated in infected pigs.These SFV infections did not markedly affect the percentage of lymphocytes in the blood and most lymphoid organs rosetting with sheep red blood cells. On the other hand, surface immunoglobulin-bearing lymphocytes were markedly increased in lymph nodes from pigs exposed to virulent SFV. The sum of both lymphocyte subpopulations in the lymph nodes from these pigs often considerably exceeded the 100% value, which strongly suggests the presence of cells bearing both surface immunoglobulin and receptors for dextran-treated sheep red blood cells.Possible correlations between these findings are discussed. The results suggest that infections with SFV induce systemic alterations in the process of lymphocyte recirculation in the pig.     

Histological, histochemical and immunohistochemical study of the haemal nodes of the dromedary camel

Haemal nodes are lymphoid organs found in various mammals and some birds. The structure of haemal nodes has been described in a number of species but not yet in the camel. Therefore, haemal nodes from 10 camels were studied histologically and tested for CD3, CD22, major histocompatibility complex (MHC) class II/DR, alpha-smooth muscle actin and for the demonstration of acid and alkaline phosphatases. The haemal nodes were of spherical or kidney shape with one or two hili and had a capsule and trabeculae of connective tissue and smooth muscles. The main parenchyma was composed of a cortex and a medulla. The cortex was formed from lymphoid follicles and diffuse interfollicular lymphocytes. The medulla consisted of lymphoid cords separated by medullary sinuses. The interfollicular lymphocytes and those in the medullary cord were CD3-positive. The lymphoid follicles showed CD22-positive cells. MHC class II/DR was expressed by most cells of the parenchyma. There were also subcapsular, peritrabecular and medullary blood sinuses. Afferent and efferent lymphatics and lymphatic sinuses were also found. Acid phosphatase-positive cells were localized mainly in the marginal, the interfollicular zone and in the medullary cord. Alkaline phosphatase positivity was observed in the endothelium of the sinuses and in the lymphoid follicles. The morphology of these organs in the camel allows a classification as haemolymph nodes and suggests involvement in blood and lymph filtration.     

First description and morphology of haemal nodes in piglets (Sus scrofa domestica)

In this study, the presence of haemal nodes, previously recognised especially in ruminants, was determined for the first time in piglets. The morphology of haemal nodes located in the abdominal cavity of seven piglets was studied by gross inspection and by histological methods. Haemal nodes reddish in colour and oval or round in shape were observed on the thin branches originating from the caudal and cranial mesenteric arteries. These nodes, having connection only with blood vessels, were covered with a thin connective tissue capsule. The haemal nodes had a hilus at the entrance of which large blood vessels were seen. These blood vessels extended into the inside of the nodes through trabeculae. Afferent and efferent lymph vessels were not observed in the haemal nodes. The nodes contained many sinuses formed by reticular fibres and reticular cells and filled by red blood cells. In the haemal nodes, lymphocytic infiltration was more commonly seen than lymph follicles.     

Architecture of sheep haemal nodes

Sheep haemal nodes are reported to be lymphatic organs within the blood circulation. In this study they were seen to be covered by a capsule of connective tissue, with a hilus in which some blood vessels were detectable. Below the capsule a subcapsular blood sinus and lymphatic nodules were present. A reticular meshwork extended through the interior; the interstices of the reticular meshwork contained a large number of free blood cells, many macrophages, lymphocytes and plasma cells. Blood collected in the subcapsular sinus and flowed through the reticular meshwork aided by the particular alignment of some of the reticular cells in channel-like passageways. Venules originated in the parenchyma and drained into efferent veins that left the organ at various points in the capsule. A large efferent blood vessel, apparently connected with the subcapsular sinus, was present in the hilus.     

La vascularisation du feuillet du boeuf)

The blood vascular system of the bovine omasum The blood vessels supplying and draining the omasal wall and laminae are described and are compared with those of other ruminants. A detailed study revealed that the subepithelial vascular networks in the papillae were in part similar to those of intestinal villi. One or more arterioles branch radially and form a capillary network which does not, as in the villus, drain into a central venule but is succeeded by several subepithelial venules. Capillaries and venules differ only in diameter which are 10 μm. and 40 μm. respectively. The walls of both have a complete basal membrane, perforated endothelium and pinocytotic vesicles. This emphasizes their significance in resorption. Inside and between the papillae the capillaries form a dense network which is separated from the basal cells by a thin layer of connective tissue 5 to 6 μm. thick. Hemodynamic problems related to the presence of elastic connective tissue and to the motor activity of the omasum are discussed.     

Anatomical localisation and histology of the ovine tonsils

The topography and histologic structure of the various tonsils were studied anatomically and microscopically in 15 sheep aged between 9 and 15 months. The palatine, pharyngeal and paraepiglottic tonsils were readily visible macroscopically. They consisted mainly of secondary lymph nodules and were encapsulated in dense connective tissues. The epithelium covering the tonsils and their crypts was frequently infiltrated heavily by lymphocytes. The tubal tonsil and the tonsil of the soft palate were macroscopically visible after fixation in 2% acetic acid. These tonsils consisted of scattered lymph nodules, aggregations of lymphocytes and diffuse lymphoid tissue. They were not encapsulated, and therefore the borders of these tonsils could not be clearly delineated. The lingual tonsil was not macroscopically visible in sheep and consisted of scattered small aggregations of lymphocytes.     

日粮中添加铁对绵羊免疫器官组织结构和铁含量的影响

为研究日粮中不同铁水平对绵羊免疫功能的影响，探究绵羊饲养过程中铁过量的风险，试验在绵羊基础日粮中分别添加铁500、1 000、1 500 mg/kg（硫酸亚铁形式），饲养75 d后宰杀，采取绵羊免疫器官（脾脏、胸腺、肝门淋巴结、十二指肠淋巴结及腭扁桃体），应用传统病理学方法观察以上器官的组织结构变化、含铁血黄素分布，并测定组织铁含量的变化情况。结果显示，绵羊饲喂过量铁后，脾脏白髓占比减小，淋巴细胞数量减少、排列疏松，伴有肿大、空泡化现象，红髓内有大量含铁血黄素沉积；胸腺皮质区变薄，髓质区变厚且融合，胸腺小体数量减少、结构模糊；肝门淋巴结、十二指肠淋巴结皮质与髓质区变薄、界限模糊，皮质淋巴窦与髓窦间隙增大，淋巴小结结构模糊；腭扁桃体实质内淋巴小结数量减少，毛细血管后微静脉有充血现象。饲喂过量铁后，各免疫器官组织铁含量均升高，其中脾脏内铁含量最多，腭扁桃体内最少，铁低、中、高剂量组脾脏铁含量极显著高于对照组（P<0.01）。结果表明，饲喂过量铁后，绵羊免疫器官组织结构均遭到不同程度破坏，且随着铁添加量越多，组织结构破坏程度越明显；各免疫器官中铁蓄积量与日粮中铁添加水平呈正相关，摄入过量铁严重影响绵羊免疫功能，因此在绵羊饲养过程中，要严格遵守美国NRC（1985）饲料标准，日粮中铁水平不要超过500 mg/kg。     

Histopathologic and immunohistochemical characterization of Nipah virus infection in the guinea pig

Mortality rate in humans infected with Nipah virus (NiV) has been reported as high as 92%. Humans infected with NiV show a widespread multisystemic vasculitis with most severe clinical and pathologic manifestations in the brain, lungs, and spleen. The purpose of this study was to study pathologic and immunohistochemical findings in guinea pigs infected with NiV. Of 28 animals inoculated intraperitoneally, only 2 survived the infection, and most died between 4 and 8 days postinoculation (dpi). Viral antigen with minimal pathologic changes was first detected 2 dpi in lymph nodes and spleen. More severe changes were noted in these organs 4-8 dpi, where pathologic damage had a vasocentric distribution and viral antigen was abundant in vascular endothelium, tunica media, adventitia, as well as in macrophages lining sinuses. The urinary bladder, uterus, and ovaries were also affected with necrosis and acute inflammation. In these organs, immunohistochemical positive staining was intense in blood vessels, epithelial cells, and ovarian follicles. Approximately 50% of the animals that died or were euthanized in extremis had evidence of viral antigen and histopathologic changes in brain, especially involving meninges and ependymal cells, with lesser changes in the neural parenchyma. A unifying feature of the damage for all affected tissues was necrosis and inflammation of the vasculature, chiefly in arterioles, capillaries, and venules. Inoculation of guinea pigs intraperitoneally with NiV produces a disease with considerable resemblance to the disease in humans, but with reduced pulmonary involvement and marked infection of urinary bladder and the female reproductive tract.     

The buccal lymph node (lymphonodus buccalis) in dogs: occurrence, anatomical location, histological characteristics and clinical implications

Three dogs were presented for clinical examination with bilateral buccal nodules which were identified as enlarged buccal lymph nodes. As little is known about this pathology, 150 dogs were examined by anatomical dissection for the presence of buccal lymph nodes. They were found in 13 dogs, occurring bilaterally in six dogs and unilaterally in seven dogs. Two buccal lymph nodes were bilobulated and one was double. The lymph nodes were always located dorsal to the zygomatic muscle and rostral to the masseter muscle in the region where the superior labial vein drains into the facial vein. Histology demonstrated a large amount of intranodal adipose tissue scattered throughout the lymphoid tissue. The canine buccal lymph node should not be confused with the accessory parotid or ventral buccal salivary gland and is clinically important as it can enlarge due to tumour metastasis or inflammation of the buccal region.     

THE ISOLATION OF SALMONELLA FROM JEJUNAL AND CAECAL LYMPH NODES OF SLAUGHTERED ANIMALS

One jejunal and one caecal lymph node were sampled from each of 50 cows, 40 yearling cattle, 25 sheep, 20 lambs and 45 pigs after slaughter. Salmonella, Clostridium perfringens and Staphylococcus aureus , all organisms which cause food poisoning in man, were sought by direct plating methods. The samples were also enriched and cultured for Salmonella. Organisms were cultured from 208 (58%) of the 360 lymph nodes; aerobic plate counts yielded up to 25,000 organisms per gram of tissue, although from most infected samples less than 1000 organisms per gram were cultured. Salmonella was isolated directly from 5% of samples, with counts up to 1,500 per gram. After enrichment Salmonella was isolated from nodes taken from 15 cows, 2 yearling cattle, one sheep and 8 pigs. Cl. perfringens was isolated from the caecal nodes of 2 yearling cattle and 2 pigs; S. aureus was not isolated from any sample. It was concluded that mesenteric lymph nodes may be a significant reservoir of Salmonella for transfer to meat and meat products.     

Effects of the adjuvant DEAE-dextran and Staphylococcus aureus on the lymph pathways and filtering capacity of popliteal lymph nodes in sheep

The effects of subcutaneous injections of the adjuvant DEAE-dextran and, or killed Staphylococcus aureus on the structure of the lymph pathways of popliteal lymph nodes in sheep were examined using light and electron microscopy and Microfil casts. Dextran with or without killed S aureus caused significant changes in the lymph pathways both within the node and outside it. However, killed S aureus alone did not. The changes included anastomoses among afferent lymph vessels and between afferent and efferent lymph vessels; proliferation of vessels around the node; joining of parts of the capsule and trabeculae to adjacent parenchyma with loss of parts of the subcapsular and trabecular sinuses; enlargement of medullary sinuses; and reduction of the number of reticular processes in sinuses throughout the node. These changes were accompanied by a reduced ability of the node to filter chicken red blood cells labelled with chromium-51 which were injected into an afferent lymph vessel.