Cytological structure of the lymph nodes after administration of foreign protein]

Changes in the cellular compositon of popliteal lymphatic nodes of albino rats were studied in normality and after injection of a foreign protein. Allergic inflammation was caused by injection of 0,25 ml of the horse serum. Observations were made on the 1, 3, 8, 19 and 30 days after the beginning of experiment. The cellular composition was counted in 30 visual fileds in the cortical plateu, follicles and myelinated cords. The average percentage of cellular elements has been determined. It has been shown that the reticular cells have less changes as compared with other cells in response to antigen stimulation. An inverse correlative relationship was noted between small and medium-sized lymphocytes. The greatest percentage of plasmic cells was noted in myelinated cords; in the follicles they are found as solitary units. In the primary immunization the cellular composition of follicles was little changed as compared with the cellular composition of the cortical and medullary substance. The cellular reaction was most pronounced in myelinated cords. Thus, the investigation of the cellular composition of different structure components of the rat's lymphatic nodes after injection of the foreign protein has revealed a different degree of their reaction.     

Features of the structure of the regional lymph nodes of the duodenum in monkeys

By means of morphometric methods, duodenal regional lymph nodes were studied in rhesus and lapunder macaques. It was demonstrated that in monkeys the connective tissue framework, cortical plateau, medullary substance, cortical substance, sinuses and follicles are expressed differently. Cellular elements in the lymph nodes analysed in the monkeys subjected to a comparative investigation demonstrated their uneven distribution in the same structural components. Small lymphocytes were predominate cellular elements. There were rather essential differences in the number of plasmic cells, mitotically dividing cells, acidophilic granulocytes, mast cells and macrophages. Certain species differences were demonstrated to exist both in structure and cell composition of the lymph nodes that seemed to depend on some local peculiarities of immunogenic reactions.     

Cytoarchitectonics of ileocecal lymph nodes in newborn and sexually mature simians (pavian hamadrils)]

Cell composition of various components (cortical plateau, folliculi and cords) of ileocecal lymph nodes was studied in newborn, 1.5 and 2.5 months of age (2 animals) and in mature (3 animals) monkeys, Papio hamadryas. In histological sections obtained at the level of hilus of the lymph node cellular elements were counted by means of morphometric grid of Glagolev modifoed by S. B. Stefanov. The data obtained were statistically treated. Newborn and mature monkeys have their peculiar cytological profile in every structural component of the lymph node. The lymph nodes in the newborns contain much more reticular cells and young cellular forms (blast forms and large lymphocytes) than mature animals. In the newborns, the number of mitotically deviding cells in the cortical plateau and in folliculi is 6 times and in myelin cords 10 times as great as in mature monkeys. A much greater per cent of plasmatic cells in mature animals suggests their greater immunological activity. Age differences in cell composition of lymph nodes in young and mature monkeys seem to be connected with accumulation of cellular mass and growth of the node in young animals, as well as with general rearrangement of the organism as a whole (in particular with changes in nutrition, intensity of movement, hormonal background).     

Structural changes in popliteal lymph nodes in the graft vs. host reaction to H-Y antigen in male C57BL/6-strain mice

Regional popliteal lymph nodes in intact, control and experimental (I, II, III groups, respectively) have been studied by means of the morphometric method in male C57Bl/6 line mice at the pick of the reaction produced by injection of spleen cells and mesenteric lymph nodes obtained from syngenic females and repeatedly immunized to H-Y antigen (10 animals in each group). Injection of the cell suspensions from the immunized and intact females of the C57Bl/6 mice result nearly in two-fold increasing mass of the regional popliteal node at the expense of enlarged size of all its zones. Changes in cytoarchitectonics of the node structural components result from redistribution of certain cellular elements. The essential changes in the cell composition of the lymph nodes in the II and III male groups are accompanied with an increasing part of the stromal reticular cells. Simultaneously, content of small lymphocytes decreases significantly. In the III group of mice there is a sharp increase in the content of young forms of the lymphoid line cells in all structural components of the node, as well as in eosinophilic granulocytes in medullary cords. In the dark cortical zone of the nodes (III group) there occur tissue basophils (mast cells), that, together with increasing number of acidophilic granulocytes and appearance of neutrophilic cells, demonstrates that there is an inflammatory reaction in the organ studied as a response to the lymphocytic suspension injected. In the experimental group of the animals a complete disappearance of plasma cells is noted in the node cortex, but some increase of their part takes place in the medullary cords.     

Alteration of the construction and cellular composition of ileo-colonic lymph nodes of rhesus macaques after administration of salmonella vaccine]

In stained histological sections, percentage ratio of areas to different cellular elements in structural components of the ileocolonic lymph nodes was studied in mature Macaca rhesus, normal and after injection of salmonella vaccine. A rather considerable reaction in all structural components and cell composition of the lymph nodes was demonstrated as a response to immunization of the animals. These changes were demonstrated in decreased area occupied by the cortical substance and in increased area occupied by the medullar substance of the lymph node. In the cortical substance, together with decrease in the cortical plateau, total number of folliculi rises with formation of light centers in them. Calculation of cellular elements revealed that in the cortical substance cytopoietic function was inhibited; that was expressed in decreasing mitoses and blast forms in the cells. Most drastic alterations occur in myelin cords of the lymph nodes. Together with increasing area, a considerable reaction of acidophilic leucocytes, premature plasma cells and macrophages is observed. Their number increases notably.     

Structure of the inguinal lymph nodes after extirpation of the pancreas

Swiching off the external and internal secretion of the pancreas by means of extirpation of the organ demonstrates a progressive hypoplasia of the immunocompetent tissue in the inguinal lymphatic nodes. The involution is determined by decreasing number of small, middle and large lymphocytes in the cortical part of the node. Together with the decreasing number of the lymphatic nodules, by the 20th-60th days after the operation the germinative centers become poor in middle, large lymphocytes and in lymphoblasts. Among the cells mentioned, mitotic activity is decreased. Hence, thymus-dependent, but to a greater extent, thymus--independent zones of the lymphatic nodes are subjected to involution.     

Microscopic structure of the mesenteric lymph nodes of monkeys]

The structure and cytoarchitectonics of mesenterial lymph nodes were studied in thin histological sections by different methods. Under study were 5 rhesus monkeys and 3 hamadryas baboons. The square surface of different structural elements of the nodes (the cortical and medullary substances, follicles, the connective tissue framework, sinuses) occupied by them in sections was calculated and the amount of cellular elements was determined (%). Comparison of the data obtained in rhesus monkeys and baboons speaks of certain species-specific features of the organs under study. The morphological picture of lymph node sections in baboons (as compared with rhesus monkeys) might suggest earlier ageing of nodes in baboons.     

Cellular composition of the lymph nodes of monkeys (rhesus macaque) under normal and experimental conditions]

By means of mathematical methods, quantitative and qualitative changes were studied in different structural components of the mesenteric (ileocecal) lymph nodes in normal monkeys (Macaca rhesus) and under per os administration of Salmonella typhi murium, streptomycin-dependent. Cellular composition was calculated in the cortical plateau, cortical (lymphoid) cords and in follicules. Average percent of every cell type was determined. Vaccine administration, was stated to inhibit cytopoiesis in the cortical plateau and in the follicules with light centers. An inverse correlation was noted between the content of small and medium size lymphocytes. Different reactivity of certain structural components in the lymph nodes was demonstrated. As a response to the vaccine administration, plasmocellular acidophilic and macrophagal reactions were most pronounced in the cortical (lymphoid) cords.     

Ileo-colonic lymph nodes in macaques and pavians of different ages]

Quantitative and qualitative alterations occurring in various structural components of the ileocolonic lymph nodes of Papio hamadryas at the age of 3.5 months and 5 years and Macaca rhesus at the age of 5 years were studied by means of mathematical methods. Cellular composition was counted in every histological preparation per 1,000 cells in cortical plateau, in myelin cords, in follicles with light centers and in follicles without light centers. Part (in %) of every cell variety was determined, as well as correlation of different structural components of the lymph nodes. Construcgion and cytoarchitectonics of the ileocolonic lymph nodes were stated to depend on the age of monkeys and their systematic differences.     

Cellular composition of various structural zones of the iliac and mesenteric lymph node of pregnant rats

The dynamic of cellular reactions demonstrates certain changes in functional activity of all structures of the node during pregnancy. A similar trend of processes in the iliac (regional for the uterus) and mesenteric lymph nodes has been defined. At early stages of pregnancy, lymph nodule are the most active, this is demonstrated as an increasing portion of lymphoblasts, macrophages and dividing cells. During this period, cell composition of the cortical plateau is relatively stable. For the paracortical zone of the mesenteric lymph nodes a rather significant decrease in the portion of middle lymphocytes and reticular cells is characteristic. There is not any significant change in the relative amount of the cells in the same functional zone of the iliac lymph nodes during the same period of pregnancy. The medullar cords demonstrate an increasing number of blast forms and young plasmocytes. However, as the pregnancy develops, the structure of the paracortical zone undergoes an essential change--progressively increases the portion of lymphoblasts and large lymphocytes. The blastic reaction in the mesenteric lymph nodes is proved to depend, to some extent, on that in the iliac lymph nodes of the same animal. Mature plasma cells become the dominating cellular element in the medullary cords. At the end of the pregnancy a relative amount of the reticular cells increases in all structural zones of the node.     

Morphology of the submandibular lymph nodes of white rats adapting to alpine conditions

A field experiment has been performed in white noninbred rats in order to study morphometrically structural reconstructions and cellular composition characteristics in the submandibular lymph nodes on the 1st, 3d, 7th, 14th, 21st, 30th and 50th days after lifting them to the altitude of 3,375 m above sea-level. The data obtained demonstrate a stable increase in small lymphocytes contents during the days of the observations; they are accompanied with an increasing specific area of the folliculi and a decreasing area of the cortical plateau. An essential decrease in the plasmic cells and dividing cells contents noted during the whole experiment is regarded to demonstrate an inhibition of the organism's immune reactivity at hypoxic hypoxia. Certain time periods are revealed which are accompanied, during the adaptation period to the high-mountain conditions, with general reactions of definite cell types and the lymph node structures: the 1st-7th days; the 14th-30th days; the 45th day and more. According to the character of the cell reactions in the experiment performed, it is possible to arrange the main structures of the submandibular lymph nodes in the following order: folliculi, cortical plateau, sinuses, medullary cords.     

Age and features of the construction and cellular composition of superior tracheobronchial lymph nodes in adult humans]

Age peculiarities in composition of the upper tracheobronchial lymph nodes have been studied in 60 corpses at the age of 16-70 years. Cause of death has not been connected with diseases of blood, lymphatic system or thoracic origins. Routine histological and morphometric methods have been applied. Certain age-dependent rearrangement in the connective tissue stroma, trabecular vegetations and differences in correlations of structural components have been noted. A rather essential volumetric increase of the medullary substance takes place at the level of hilus of the lymph node. Cellular composition of the lymph nodes is greatly polymorphous but is more or less constant for each age group. The number of macrophages containing carbon pigment is increasing with age.     

Ontogeny of human fetal lymph nodes.

Developing lymph nodes from 30 human embryos and fetuses with crown-rump lengths (CRL) of 18 mm (5.6 wk) to 245 mm (26 wk) were examined by light microscopy. The nodes were embedded in araldite, and the sections examined were approximately 1 mu in thickness. The development of nodes was divided into three stages: 1. the lymphatic plexus and connective tissue invagination (30 mm to 67 mm CRL); 2. the early fetal lymph node (43 mm to ,5 mm CRL); and 3. the late fetal lymph node (CRL greater than 75 mm). The lymphatic plexus was formed by connective tissue invaginations and bridges which divided a lymph sac into a meshwork of channels and spaces. Connective tissue invaginations were endothelially-lined and were surrounded by lymphatic space. Reticular cells, macrophages, and blood vessels were found in these invaginations. Early fetal lymph nodes were formed from invaginations when the cellular density and lymphocyte content increased. The lymphatic space surrounding the early node was the developing subcapsular sinus. With further development the early node became packed with lymphocytes, increasing the cellular density and size of the node. The connective tissue surrounding the subcapsular sinus condensed to form the capsule. Afferent lymphatic vessels pierced the capsule. Capillaries, veins, postcapillary venules, and occasional arteries were found in early and late nodes.     

Morpho-functional changes in the lymph nodes during fever reaction]

Lymph nodes (mesenteric, popliteal, cervical) of rabbits in fever reaction of different duration have been studied in our work. As a whole morpho-functional changes in lymph nodes in fever reaction indicate the increase of their functional activity: hyperplasia of lymphatic substance with the growth of lymphocytes number and slightly differentiated lymphoid cells in follicles and paracortical zone, hyperplasia of pulposus bands, the signs of macrophagal reaction and plasmatization of lymph nodes are to be observed and all these create prerequisites for the increase of tensity of cellular and humoral immunity. Simultaneously the signs of destruction of cellular elements--lymphocytolysis in the porta tract and the growth of number of PAS-positive cells in the parenchyma of the nodes take place.     

Study of the lympho- and hemomicrocirculatory bed of lymph nodes by scanning electron microscopy

The spatial interrelation of the lymphatic and blood beds has been studied in the lymph node together with its stromal and lymphoid elements, using scanning electron microscopy of corrosive casts and native preparations. There is a great variety of pathways for lymph transport and blood vessels in dependence of their localization in the lymph node. Of a special interest are the pathways of lymphocytes migration across the walls in the cortical and medullary sinuses and in the postcapillary venules, as well as participation of the reticular tissue in the lymph node immune reactions.     

The localization of CD3, CD79a,CD68 and S100 protein immunoreactive cells in hemal nodes of Saanen goat (Capra hircus)

We investigated the structure of hemal nodes in Saanen goats using immunohistochemical staining. We examined the distribution of CD3 positive T lymphocytes, CD79a positive B lymphocytes, CD68 positive macrophages and S100 protein positive follicular dendritic cells. Hemal nodes of six healty adult female goats were used. Hemal nodes were removed from the thoracic and abdominal cavities. The oval to round hemal nodes were observed especially between the abdominal aorta and vena cava, and near the kidneys and adrenal glands. Tissue sections were stained with Crossmon’s modified triple stain to demonstrate general histological structure. The avidin-biotin-peroxidase technique using anti-CD3, anti-CD79a, anti-CD68 and anti-S100 primary antibodies was used for immunohistochemistry. Many CD3 positive T lymphocytes were found in the germinal center of the lymph follicles and in the lymphatic cords of hemal nodes; CD3 positive cells also were observed in the sinuses. CD79a and CD68 positive cells were found at the germinal center of the lymph follicles. In the lymph follicles near the subcapsular sinuses, CD79a and CD68 positive cells were found especially in e areas bordering the mantle zone. S100 positive cells were found in the lymph follicles, lymphatic cords and sinuses.     

Entamoeba histolytica: lymphoreticular changes in gerbils (Meriones unguiculatus) with experimentally induced cecal amebiasis

Antibody responses and changes in the lymphoreticular tissues of gerbils with experimental cecal amebiasis were studied from 5 to 60 days PI. Changes in the cecum consisted of lymphoid follicle hyperplasia and depletion of lymphocytes, followed by follicle atrophy and histiocytosis. Mesenteric lymphadenopathy, and histologic alterations in the lymph nodes paralleled the progressive development of amebic cecal lesions. Early in the infection (5 to 10 days PI) mesenteric lymph nodes showed cortical follicle hyperplasia, blastogenesis in the paracortical areas (PCA) and intense lymphoblast and plasma cell activity in the medullary cords. At 20 to 30 days PI, the cortical follicles, the PCA and the medulla were depleted of lymphocytes and there was histiocytosis throughout the organ. At 60 days PI, lymphocyte repopulation took place in the PCA, and cortical follicles had active germinal centers. Spleen follicles did not increase in number as the infection progressed, but became hyperplastic. Antibody titers to ameba were low throughout the cecal infection but rose whenever amebic metastasis to the liver occurred. The results of this study indicate that lymphocytes from the submucosal lymphoid follicles and the draining lymph nodes may control the pathogenesis of the infection. Lymphoreticular tissue alterations could result from antigenic stimulation and migration of cells to the sites of infection.     

Ontogeny of the antigen-reactive lymph follicle-forming capacity of the popliteal lymph node in neonatal mice

The ontogenetic development of the reactive lymph follicle-forming capacity of the popliteal lymph node was investigated immunohistochemically in young mice which had received a single injection of hemocyanin (KLH) in a rear footpad at a predetermined age (between 1 and 21 days). The mice were sacrificed at various intervals after injection. In non-stimulated young mice, primary lymph follicles first appeared in the popliteal node at 11 days of age. When KLH was given to 7-day-old or older mice, each draining popliteal node showed a marked increase in B lymphocytes in the extrafollicular zone 3 days after injection and produced a number of "new" lymph follicles outside the pre-existing follicles over the next few days. In mice injected at 2-4 days of age, these nodes showed an increase in B lymphocytes in the outer cortex and had produced several lymph follicles by 8 days of age. The number of lymph follicles produced by each node tended to increase in line with age at injection. These results indicate that neonatal popliteal nodes become able to produce lymph follicles in response to exogenous antigens some time before ontogenetically developing follicles appear. The formation of new lymph follicles observed in draining popliteal nodes after KLH injection at an early postnatal age is discussed in relation to the ontogenetic development of stromal cells (precursors of follicular dendritic cells) that are capable of interacting with B lymphocytes and the extent of B lymphocyte influx into the node induced by KLH stimulation.     

Ultrastructural analysis of lymph node innervation in the rat

The morphological analysis of nerves in axillary lymph nodes of the rat revealed the presence of two types of axon possessing either a more or a less electron-lucent matrix. The more electron-lucent axons enter the node finely myelinated, do not contain synaptic vesicles and quickly divide to form branches approaching the basement membranes of blood vessels, as well as cellular elements. They may be interpreted as sensory axons. The less electron-lucent axons are unmyelinated, and contain three distinct populations of synaptic vesicles. These may all be present in one axonal varicosity, so that the existence of cotransmitters is highly probable.     

The influence of afferent lymphatic vessel interruption on vascular addressin expression

Tissue-selective lymphocyte homing is directed in part by specialized vessels that define sites of lymphocyte exit from the blood. These vessels, the post capillary high endothelial venules (HEV), are found in organized lymphoid tissues, and at sites of chronic inflammation. Lymphocytes bearing specific receptors, called homing receptors, recognize and adhere to their putative ligands on high endothelial cells, the vascular addressins. After adhesion, lymphocytes enter organized lymphoid tissues by migrating through the endothelial cell wall. Cells and/or soluble factors arriving in lymph nodes by way of the afferent lymph supply have been implicated in the maintenance of HEV morphology and efficient lymphocyte homing. In the study reported here, we assessed the influence of afferent lymphatic vessel interruption on lymph node composition, organization of cellular elements; and on expression of vascular addressins. At 1 wk after occlusion of afferent lymphatic vessels, HEV became flat walled and expression of the peripheral lymph node addressin disappeared from the luminal aspect of most vessels, while being retained on the abluminal side. In addition, an HEV-specific differentiation marker, defined by mAb MECA-325, was undetectable at 7-d postocclusion. In vivo homing studies revealed that these modified vessels support minimal lymphocyte traffic from the blood. After occlusion, we observed dramatic changes in lymphocyte populations and at 7-d postsurgery, lymph nodes were populated predominantly by cells lacking the peripheral lymph node homing receptor LECAM-1. In addition, effects on nonlymphoid cells were observed: subcapsular sinus macrophages, defined by mAb MOMA-1, disappeared; and interdigitating dendritic cells, defined by mAb NLDC-145, were dramatically reduced. These data reveal that functioning afferent lymphatics are centrally involved in maintaining normal lymph node homeostasis.