Hemal Nodes Research Articles

Differential expression and localization of immunity-related factors in main immune organs of yak

The yak is an agricultural animal with strong disease resistance in Qinghai–Tibet Plateau. Immune organs are directly involved in the body’s immune response and protect it from external aggression. In this study, we characterized and evaluated the main markers of interleukin (IL)-1β, IL-17a, hypoxia inducer factor-1 (HIF-1)α, and heat shock protein 90 (HSP90) in the lymph nodes, spleen, thymus, and hemal nodes of adult yaks using network informatics, molecular cloning, immunohistochemistry, real-time quantitative polymerase chain reaction (RT-qPCR), and western blotting. We first cloned the IL-1β and IL-17a mRNA of yaks. A significant feature was the higher IL-1β and IL-17a expression in the lymph nodes than in the spleen, hemal nodes, and thymus. Immunohistochemistry and immunofluorescence revealed that IL-1β and IL-17a cells were mainly located in the paracortex area of the lymph nodes and the T-cell-dependent area in the hemal nodes and spleen. Several HIF-1α proteins were detected in the cortex of the hemal nodes mantle, while HSP90 was detected in the lymphoid nodules of the hemal nodes and lymph nodes. This study sheds light on the relationship between the morphology and function of these organs and provides an important reference for studies on the participation of yak immune organs in immune responses.

Laboratory analysis as support to slaughterhouse inspection in Songea cattle abattoir (Tanzania): A public health perspective.

Livestock breeding is one of the main agricultural activities in Tanzania, recognized as one of the African countries with the greatest livestock resources. Cattle is the most widely bred animal species, especially with traditional farming methods such as pastoralism and agro-pastoralism. Slaughtering takes place mainly in rural slaughter slabs and municipal slaughterhouses, and according to local legislation it must be supervised by Official Veterinarians, who report any organs to be discarded and, after stamping the carcass, authorize its free consumption. Since the Ruvuma region lacks data on cattle diseases, the aim of this study was to collect information at Songea slaughterhouse, with particular attention to conditions of parasitic aetiology and potential zoonotic interest, deepening inspective diagnoses by means of parasitological and histological investigations on tissue samples. Overall, the slaughter data of 614 animals are reported. In most cases slaughtered cattle belonged to local breeds and came from the Mbeya region. Fasciolosis (diagnosed in 44.6% of animals) was the most frequent condition, followed by respiratory diseases (24.4%), aortic onchocerciasis (6.5%), hydatidosis (5.5%) and bovine cysticercosis (3.4%). Laboratory analysis identified Fasciola gigantica as the species involved in hepatic distomatosis in this area. Cases macroscopically ascribed to cysticercosis turned out to be a muscular form of onchocerciasis (by Onchocerca dukei), a neglected and unrecognised parasitic disease in Tanzania, questioning the real frequence of a zoonosis that causes primarily major economic losses. Pulmonary cysts, referred as hydatidosis at visual inspection, were histologically identified as haemal nodes, lymphoid organs common in ruminants, but described in cattle lungs for the first time in the present paper. Slaughterhouse is an important epidemiological observatory, especially for neglected parasitoses. The possibility of having basic laboratory diagnostics as an aid to visual inspection can ensure greater efficiency of veterinary services in the control of important livestock diseases and zoonoses, in the frame of a One Health perspective.

Expression characteristics of immune factors in secondary lymphoid organs of newborn, juvenile and adult yaks (Bos grunniens)

Little is known about lymphoid organ development in yaks. In this study, we characterize and evaluate the main markers of T cell, B cell, plasma cell and antigen-presenting cell in the mesenteric lymph nodes, spleen and hemal node in newborn, juvenile and adult yaks by immunohistochemistry, real-time quantitative polymerase chain reaction and western blotting. The structures of all organs were not fully developed in newborn. The CD3+ cells were mainly located in the paracortex area of the mesenteric lymph node and the T cell dependent area in the hemal node and spleen. CD79a+ cells were mainly detected in the lymphoid follicles. The expression of CD3 and CD79a increased from newborn to juvenile and then decreased in adults. The expression of CD3 was always higher in the spleen and CD79a was higher in the mesenteric lymph node. IgG+ and IgA+ cells were observed in all examined samples, except in newborn yak hemal node. IgG and IgA were up-regulated with age and the highest expression was observed in the mesenteric lymph node. The SIRPα and CD68 were widely expressed. A significant feature was that the SIRPα expression in the spleen was lowest in newborns but highest in juvenile and adult yaks. The expression of CD68 in the hemal node was highest in all groups and increased from newborn to adult yaks. This study sheds light on the relationship between the morphology and function of these organs and provides useful references for normal yak lymphoid organ development.

Varieties of atypical lymph nodes of water deer (Hydropotes inermis argyropus)

The morphology and topography of atypical lymph nodes of Korean water deer (Hydropotes inermis argyropus) is described for the first time. The aim of this work was to study the structural organization of atypical lymph nodes in water deer. Fresh organ samples were taken from 5 adult water deer. Samples are fixed in formalin and embedded in paraffin wax (Hystomix). Stain serial sections, 4-5 μm thick, are stained with hematoxylin-eosin, Masson’s trichrome stain, Gomori’s silver impregnation stain. Atypical lymph nodes in Korean water deer are located on the trachea along the jugular vein and under the trachea on the internal carotid artery and internal jugular vein. The nodes are localized on the adipose tissue of the pericardium in the thoracic cavity, as well as directly on the aortic arch. In the abdominal cavity, nodes are located along the caudal cava and abdominal aorta, as well as in the connective tissue layers of the pancreas. Organs have a dark red color, oval or round shape, its size - from millet grain to peas. Atypical lymph nodes are heterogeneous organs that differ not only from the usual lymph nodes, but also from each other, both in the type of bringing vessels and some features of the structure. Based on a detailed morphological study, atypical lymph nodes in the abdominal cavity were subdivided into 3 types: 1) hemolymphatic nodes; 2) venous hemal nodes and 3) arterial hemal nodes.

Zoological terms in the human histological nomenclature Terminologia Histologica. What we think, what we know, and what we think we know

Terminology in morphological and zoological sciences is enormously important. Proper denomination of individual structures of the animal / human body from the microscopic point of view has an irreplaceable role in unambiguous understanding and communication among scientists regardless of their field of expertise. The year 2008 can be considered a crucial year in the developing of internationally accepted histological terminology, because it was the year when the first internationally renowned human histology nomenclature Terminologia Histologica was published. The current version of the Terminologia Histologica contains also the description of many microscopic organs and structures whose presence in different animal species is widely accepted, however their presence in humans is disputable. Typical examples are the haemal lymph nodes and haemal nodes, mentioned in the chapter Lymphoid organs which are secondary lymphoid organs found in many different mammalian species, but also in some birds. They are capable of performing haematopoietic and immunological functions but in the absence of lymphatic system pathology, no structures resembling haemal nodes / haemal lymph nodes have been detected in humans. Neurohaemal organs are mentioned within the chapter Endocrine system. Neurohaemal organs are known by different names, depending on the animal species studied, e.g. corpora allata or abdominal perisympathetic organs. To this date, these structures have been described in many different invertebrate species, but neurohaemal organs are also found in some lower vertebrates, in which the neurohaemal organ is referred to as “urophysis”. According to our opinion, structures called neurohaemal organs in invertebrates are counterparts to circumventricular organs found in vertebrates, but cannot be named as such. Another somewhat controversial term mentioned in human histological nomenclature is the vomeronasal organ mentioned in the chapter Respiratory system. It is a specialized organ, which forms an integral supportive part of the olfaction of many mammalian species and reptiles. It is believed that the main function of vomeronasal organ is to regulate various behavioral aspects of intraspecies interaction by facilitating the detection of pheromones. The function and even existence of the vomeronasal organ in humans is a source of significant dispute among researchers. Some of them stated that vomeronasal organ disappears during fetal development, with except the vomeronasal duct. On the other hand, there are also authors who concluded that the vomeronasal organ is definitely present in adult humans. Similarly disputable question is the presence of multinucleated plasmodia in human body. This opinion article aims to open a wide scientific discussion concerning the importance and aptness of the inclusion of these terms in the human histological nomenclature despite they are probably exclusively zoological.

Enzyme Histochemistry of Hemal Nodes of Indian Buffalo (Bubalus bubalis)

The present study was conducted on hemal nodes of buffalo to study the histoenzymic distribution of phosphatases and oxidoreductases. The fresh unfixed buffalo hemal nodes were immediately collected after sacrifice and were subjected to cryostat sectioning at -200 C with cryostat microtome. The sections were incubated with substrates for demonstration of various enzymes. The study revealed that in both the groups, weak alkaline phosphatase (AKPase) activity was observed in capsule of the hemal node. The AKPase activity was moderate in subcapsular sinus, periphery of lymphoid follicles and diffused lymphocytes. Uniform weak Glucose 6-phosphate activity was observed in entire hemal node. Succinic dehydrogenase (SDH) activity was moderate in capsule and lymphoid follicles and weak in subcapsular sinuses. Lactic dehydrogenase activity was moderate to strong in capsule, sub-capsular sinus and peripheral area of lymphoid follicles. Nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-D) and reduced Nicotinamide adenine dinucleotide diaphorase (NADH-D) was weak to moderate in the capsule and moderate to strong in lymphoid follicles. The presence of variable activity of different enzymes in hemal nodes was correlated with maturation of lymphocytes and development of different metabolic pathways.

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.

Comparison of histological characteristics and expression of CD3 and CD79a among the hemal nodes, lymph nodes and spleens of yaks (Bos grunniens).

This experiment compared the histological characteristics and distribution of CD3 and CD79a among yak lymph nodes, hemal nodes and spleen. The three organs from ten clinically healthy newborn and adult yaks were studied using histology and immunohistochemistry. The yak hemal nodes, which consisted of blood sinuses, lymphoid follicles, diffuse lymphoid tissue and lymphoid cords, appeared to share the histological characteristics of the spleen and lymph nodes: the lymphoid follicles of the hemal nodes were much like those of the lymph nodes, which were not surrounded by the central artery and periarteriolar lymphoid sheath. The lymphoid cords of the hemal node, which contained many erythrocytes, were much like the splenic cords. The sinuses of the hemal nodes had a similar structure to the lymph sinuses of the lymph nodes but were engorged with erythrocytes rather than lymph as in the lymph nodes. Interestingly, the splenic sinuses of yak were of two different types: the sinuses with obvious endothelial cells or those consisting of reticular cells. The CD3+ cells were mainly located in the paracortex area and medulla of the lymph nodes, the diffuse lymphoid tissues of the hemal nodes, and the periarteriolar lymphoid sheaths and red pulp of the spleen. Most CD79a+ cells were mainly detected in the lymphoid follicles of all examined lymphoid organs. The results suggested that although the three organs had specific characteristics, in some respects, they had similar organizational structural characteristics and immune functions. These may be useful to better understand the relationship between the morphology and function of these organs and provide useful references for normal yak lymphoid organs.

Immunohistochemical study on roe deer haemal nodes.

The aim of this study was to investigate the immunohistochemical characteristics of the haemal nodes located in the abdominal and thoracic cavities in roe deer (Capreolus capreolus). In this study, 2 adult male and 2 adult female roe deers in addition to 2 roe deer foetuses at the late foetal stages were used. The avidin-biotin-peroxidase technique was applied to anti-CD3, anti-CD79acy, anti--macrophage, anti-S100 primary antibodies. Positive results were gained for all the antibodies used. Many CD3 positive T-lymphocytes were seen in the lymphoid tissue areas of the foetal haemal nodes, in the germinal centre of the lymph follicles of the adult haemal nodes and in their lymphatic cords. CD79acy positive cells were less in number while S-100 protein was positive in both lymph follicles and in sinuses of the adult haemal nodes. In foetal haemal nodes, cells positive for S-100 protein were more prevalent in the sinuses. For the MAC387 primary antibody, there were positive macrophages seen in the capsule and trabeculae of the haemal nodes, located denser in males. Macrophage cells in the lymphoid structures and granulocytes in the sinuses of the haemal nodes of both adults and foetuses were positive for MAC387. This study is the first one to define the detailed structural features immunohistochemically in the haemal nodes of the roe deer. Even it's concluded that the results were similar with the other ruminants, it's also pointed out that there are certain differences among the foetal, adult male and female haemal nodes of the roe deer. (Folia Morphol 2018; 77, 2: 266-271).

Peculiarities of cellular composition and microarchitecture of human hemal nodes.

Background. Cellular composition of lymph nodes is well described while in hemal nodes it is still poorly investigated. Objective. To define peculiarities of distribution of major types of immunocompetent cells and stromal elements in human hemal nodes. Methods. Hemal nodes were taken during autopsy from patients who died due to cardiovascular or respiratory pathology. Standard histological and immunohistochemical methods were used to detect different cellular types and stromal elements. Results. Distributions of lymphocytes was investigated with the help of anti-CD20, CD3 and CD8 antibodies. To analyze dendritic cells and macrophages anti S100 and CD68 antibodies were used. Stromal elements were detected with the help of anti SMA and CD34 antibodies. Conclusion. Hemal nodes have the same character of immune cells’ distribution as in lymph nodes, except B-cells, which are equally present in paracortex and medullary cords. Among well-developed intranodal vasculature there were revealed CD34-negatve vessels, which are also known in literature as system of conduits.

Distribution of T-cell markers CD4 and CD8α in lymphoid organs of healthy newborn, juvenile, and adult highland-plateau yaks.

To investigate the distribution of T-cell markers (CD4 and CD8α) in lymphoid organs of newborn, juvenile, and adult yaks. 15 healthy male yaks of various ages from highland plateaus. Yaks were allocated to groups on the basis of age (newborn [1 to 7 days old; n = 5], juvenile [5 to 7 months old; 5], and adult [3 to 4 years old; 5]). The thymus, spleen, 5 mesenteric lymph nodes, and 5 hemal nodes were harvested from each yak within 10 minutes after euthanasia. Morphological characteristics of those lymphoid organs were assessed by histologic examination; expression of CD4 and CD8α mRNAs and proteins were measured by quantitative real-time PCR assay and immunohistochemical staining. Among the lymphoid organs evaluated, expressions of CD4 and CD8α mRNAs were highest in the thymus in all age groups. In newborn lymphoid organs, CD4 mRNA expression and CD4+ cell distribution were more predominant, whereas in juvenile and adult lymphoid organs, CD8α mRNA expression and CD8α+ cell distribution were more predominant. The CD4+ and CD8α+ cells were mainly located in the cortex and medulla of the thymus, the medulla of the hemal nodes and mesenteric lymph nodes, the periarteriolar lymphoid sheaths, and the red pulp of the spleen. Results indicated that the CD4 mRNA expression and CD4+ T-cell distribution in yak lymphoid organs decreased and CD8α mRNA expression and CD8α+ T-cell distribution increased with age. Moreover, CD8α+ cells were present in the follicles of yaks' secondary lymphoid organs, which differs from findings for other mammals.

A Light microscopic investigation on the histology and alpha-naphthyl acetate esterase (ANAE)- and acid phosphatase (ACP-ase) positive lymphocyte localization in the hemal nodes of Yaks (Bos grinniens)

A Light microscopic investigation on the histology and alpha-naphthyl acetate esterase (ANAE)- and acid phosphatase (ACP-ase) positive lymphocyte localization in the hemal nodes of Yaks (Bos grinniens)

DEVELOPMENTAL FEATURES OF PORCINE HAEMAL NODES: A HISTOLOGICAL PERSPECTIVE

Histological techniques were employed to provide detailed information on the histological features of haemal nodes in piglets and adult pig. Ten pigs were used for this study. The result demonstrated progressive changes in the structure of porcine haemal nodes. The capsule and trabeculae of piglet haemal nodes exhibited dense irregular connective tissues with reticular cells and smooth muscle cells. The cortex was more central while the medulla was peripheral with poorly defined boundaries. However, the sinusoids contained less densely packed erythrocytes. In adult pigs, haemal nodes demonstrated capsules composed of loose irregular connective tissue, fat cells, and mostly reticular cells while the trabeculae showed dense irregular connective tissues with reticular cells and smooth muscle cells. The atypical cortex and medulla of adult pig haemal nodes were distinct. The paracortex of adult pig haemal node showed high endothelial venules and the sinusoids contained densely packed erythrocytes. Afferent lymphatics, efferent lymphatics, blood vessels and veins were observed in the haemal nodes of piglets and adult pigs. Finally, the present study has provided essential information on the structural features of haemal nodes in piglets and adult pigs, revealing its atypical nature, and probable roles of blood storage, erythrophagocytosis and immune functions.

Distribution of Porcine Haemal Nodes and Morphological Variations in the Haemal Nodes of Cattle and West African Dwarf Goats

Apparently healthy, non-lactating, non-gravid adult large white pigs (15), adult cattle (10) and adult West African Dwarf (WAD) goats of either genders were used to investigate the morphology of haemal nodes using gross anatomical and histological techniques. The results demonstrated that the haemal nodes of pigs occurred in the thoracic, abdominal and pelvic regions along the course of blood vessels. The ranges of the longest diameters of the dark brown organs were 6.1 – 30.3 cm in pigs, 4.1 – 18.7 cm in cattle and 2.7 – 8.2 cm in WAD goats. Bovine haemal nodes showed cortical and medullary parenchymal areas, with the cortex demonstrating primary and secondary lymphoid follicles in a circumferential fashion. The medulla showed blood filled medullary sinusoids and medullary cords. In WAD goat, the reticular cells and smooth muscle cells of the capsule were oriented in different directions and the subcapsular, cortical and medullary sinusoids exhibited erythrocytes in pockets. In conclusion, the present study has provided information on the distribution of haemal nodes in pigs as well as other unique morphological features of cattle and WAD goat haemal nodes that could aid their identification and suggest their roles in the body.

Subtypes of human atypical lymph nodes, defined based on comparative morphological analysis.

Background. Lots of articles describe structure of lymph nodes with blood in their sinuses, but there are still many controversies between them due to the absence of single system of classification. Objective. The purpose of this work was to characterize the structure of human atypical lymph nodes and offer the new system of their classification. Methods. Atypical lymph nodes were taken during autopsy from patients who died due to cardiovascular or respiratory pathology. Standard histological methods were used including staining with hematoxylin and eosin. Results. Based on comparative morphological study we subdivided all atypical lymph nodes into three subtypes. I - Hemolymph node – it receives mixture of blood and lymph; during filtration through the system of sinuses all erythrocytes are eliminated, while efferent lymph vessels receive pure lymph. Such nodes are usually revealed close to kidneys and spleen. II – Hemal nodes – they receive blood through direct communication between blood vessels and sinuses; depending on the type of afferent vessel they are further subdivided into arterial and venous. Their efferent vessels contain blood with comparatively high content of leukocytes. III – Hyperemic lymph node – there are no afferent vessels bringing blood to the sinuses, but there are lots of dilated blood vessels with signs of hemoconcentration. All atypical lymph nodes contain different number of extravasated erythrocytes, assuming the possibility to filtrate blood antigens. Conclusion. Analyzing different types of human lymph nodes we offer a new system of their classification; the major criteria are summarized in the article.

Hemal Node of Egyptian Water Buffalos (Bos Bubalus): It’s Role in Erythrophagocytosis

Hemal nodes were obtained from 12 clinically healthy male buffalos aged 2-3 years, their average weight is 500-600kg. Electron microscopy revealed macrophages engulfing intact erythrocytes in vacuoles, or only parts of erythrocytes appeared in the vacuoles. Some electron dense material appeared in the erythrocyte as a lysosomal degrada- tion. Also myeline like figures and residual bodies were seen in macrophages cytoplasm.

A mechanism for selective lymphocyte homing in bovine hemal nodes

The distribution and abundance of MECA-79+ cells in bovine hemal nodes (HNs) was analyzed. In addition, T cell subsets which expressed the homing receptor l-selectin were analyzed by flow cytometry. The frequency of MECA-79+ HNs varied depending on the location. There were 61, 33, and 17% MECA-79+ HN in the subcutaneous region, along the abdominal aorta and in the mesenteric region, respectively. MECA-79+ cells in mesenteric lymph nodes were mainly distributed in the paracortex. Many MECA-79+ cells were distributed in the perifollicular area of HNs and a few positive cells were also located in the paracortical and interfollicular areas. CD4+ and CD8+l-selectin+ cells were significantly higher in MECA-79+ HNs compared to MECA-79− HNs. The data suggest that a selective lymphocyte homing mechanism exists in bovine HNs, which could be related to functional differences between locations.

Accumulation profiles of PrPSc in hemal nodes of naturally and experimentally scrapie-infected sheep

BackgroundIn classical scrapie, the disease-associated abnormal isoform (PrPSc) of normal prion protein accumulates principally in the nervous system and lymphoid tissues of small ruminants. Lymph nodes traffic leukocytes via lymphatic and blood vasculatures but hemal nodes lack lymphatic vessels and thus traffic leukocytes only via the blood. Although PrPSc accumulation profiles are well-characterized in ovine lymphoid tissues, there is limited information on such profiles in hemal nodes. Therefore, the objective of this study was to compare the follicular accumulation of PrPSc within hemal nodes and lymph nodes by prion epitope mapping and western blot studies.ResultsOur studies found that PrPSc accumulation in 82% of animals’ abdominal hemal nodes when PrPSc is detected in both mesenteric and retropharyngeal lymph nodes collected from preclinical and clinical, naturally and experimentally (blood transfusion) scrapie-infected sheep representing all three major scrapie-susceptible Prnp genotypes. Abdominal hemal nodes and retropharyngeal lymph nodes were then used to analyze immune cell phenotypes and PrPSc epitope mapping by immunohistochemistry and PrPSc banding patterns by western blot. Similar patterns of PrPSc accumulation were detected within the secondary follicles of hemal nodes and retropharyngeal lymph nodes, where cellular labeling was mostly associated with macrophages and follicular dendritic cells. The pattern of PrPSc accumulation within hemal nodes and retropharyngeal lymph nodes also did not differ with respect to epitope mapping with seven mAbs (N-terminus, n = 4; globular domain, n = 2; C-terminus, n = 1) in all three Prnp genotypes. Western blot analysis of hemal node and retropharyngeal lymph node homogenates revealed identical three banding patterns of proteinase K resistant PrPSc.ConclusionDespite the anatomical difference in leukocyte trafficking between lymph nodes and hemal nodes, the follicles of hemal nodes appear to process PrPSc similarly to lymph nodes.

Scanning Electron Microscopic Study of the Vascular System in the Hemal Node of the Bovine Cervical Region

The vasculature of the hemal node (HN) from the bovine cervical region was investigated using a combination of vascular corrosion casting and scanning electron microscopy. A dense vessel network of capsule was found surrounding the cast of HN parenchyma and had no connection with the subcapsular sinus; these vessels converged and exited the HN via the hilar vein. Within the HN, many anastomoses were found between the capillary networks and the surrounding sinuses in the follicular zone and deep cortex. The sinusoid pathway in the HN was characterized by subcapsular sinuses, which were continuous with the trabecular sinuses and tubular sinuses over the parenchyma, and these sinuses finally entered the medullary veins. In our study, direct communications between cortical capillaries and subcapsular sinuses were identified. This may explain the origin of numerous erythrocytes in the HN sinusoids and help to understand lymphocyte migration of the HN.

Histological and Immunohistochemical Study on Iberian Red Deer (Cervus elaphus hispanicus) Haemal Nodes

Haemal nodes are capsulated, lymphoid organs with haemal circulation. Their parenchyma is distributed in primary and secondary lymphatic nodes in the cortical and medullar zones. In these zones the lymphatic tissue may adopt a cord-like shape and it is composed by plasma cell, macrophages and B and T lymphocytes. Blood circulates through the sinuses situated underneath the capsule, around the trabeculae and in the marrow.