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

Haemolymph node - an immunomorpholoigcal organ: modeling the haemolymph node by allografting renal tissue in the rat

There is no authoritative identification of the attributes of the haemolymph node since Gibbes first described it in 1884. Early literatures showed that it was found near the kidney in human and animals with the characteristics of numerous erythrocytes in sinuses. Subsequent studies were mainly focused in the field of anatomy and histology, such as the source, distribution and quantity of erythrocytes in sinuses. Recent articles mentioned that the emergence of the haemolymph node was related to immunity, but there was no strong evidence to support the hypothesis. Therefore it is still uncertain whether the haemolymph node is an organ of anatomy, histology or immunology. It has been found that the development of the haemolymph node can be elicited in the parathymic area by stimuli such as Escherichia coli, allogeneic breast cancer cells and renal tissue that were injected/transplanted into the tail of rats in our pilot studies. In this study, the model of the haemolymph node was established by transferring the allogeneic renal tissue in the rat. Intrasinusoidal erythrocytes of the node were the component for producing a red macroscopic appearance, while macrophage-erythrocyte-lymphocyte rosettes were the major immunomorphological changes, which reflects the immune activity against the invasion of the allogeneic tissue within the node. Therefore the haemolymph node is an immunomorphological organ.

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.

Evaluation of a panel of antibodies for the immunohistochemical identification of immune cells in paraffin-embedded lymphoid tissues of new- and old-world camelids

Different species of camelids play an important role in the epidemiology of various emerging infectious diseases such as Middle East respiratory syndrome. For precise investigations of the immunopathogenesis in these host species, appropriate immunohistochemical markers are highly needed in order to phenotype distinct immune cells populations in camelids. So far, specific immunohistochemical markers for camelid immune cells are rarely commercially available, and cross-reactivity studies are restricted to the use of frozen dromedary tissues. To bridge this gap, 14 commercially available primary antibodies were tested for their suitability to demonstrate immune cell populations on formalin fixed paraffin-embedded (FFPE) tissue sections of dromedaries, Bactrian camels, llamas, and alpacas in the present study. Out of these, 9 antibodies directed against CD3, CD20, CD79α, HLA-DR, Iba-1, myeloid/histiocyte antigen, CD204, CD208, and CD68 antigen exhibited distinct immunoreaction patterns to certain camelid immune cell subsets. The distribution of these antigens was comparatively evaluated in different anatomical compartments of thymus, spleen, mesenteric, and tracheobronchial lymph nodes. The presented results will provide a basis for further investigations in camelids, especially with respect to the role of the immune response in certain infectious diseases, which harbor a considerable risk to spill over to other species.

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.

Histological and enzyme histochemical investigation of the hemal nodes of the hair goat

We investigated the structure of the hemal node in six healthy hair goats using histological and enzyme histochemical methods. After processing, tissue sections were stained with Crossman's trichrome, Gordon-Sweet's silver and Pappenheim's panoptic stains. Alpha-naphthyl acetate esterase (ANAE) and acid phosphatase (ACP-ase) were demonstrated in frozen sections. Hemal nodes were encapsulated by connective tissue and few smooth muscle cells. Several trabeculae originated from the capsule and extended into the hemal node. A subcapsular sinus was present beneath the capsule and was continuous with the deeper sinuses. Subcapsular and deep sinuses were filled with erythrocytes. The parenchyma consisted of lymphoid follicles, diffuse interfollicular lymphocytes and irregular wide lymphoid cords. Cortical and medullary regions were not distinct. ANAE (+) and ACP-ase (+) cells were located mainly in the germinal centers of the lymphoid follicles and also were scattered equally in the interfollicular region and lymphoid cords. Monocytes, macrophages and reticular cells displayed a diffuse positive reaction, whereas localized granular positivity was observed in lymphocytes. We demonstrated that the general structure of the hair goat hemal nodes is similar to that of other ruminant species.

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.

Morphology of haemal nodes in the roe deer (Capreolus capreolus)

The present study was aimed at the determination of the morphology of haemal nodes in the roe deer (Capreolus capreolus). The morphology of haemal nodes located in the abdominal and thoracic cavities of six roe deer (two adult male, two adult female and two foetuses) was studied by gross inspection and histological methods. Oval- and round-shaped haemal nodes with colours varying from pink to dark red were observed particularly between the abdominal aorta and caudal vena cava, and at the beginning of the main branches of the abdominal aorta. These nodes, having connection only with blood vessels, were covered with a thin or thick capsule of connective tissue in the foetus and the adult respectively. Trabeculae were not observed in foetal nodes. In adults, the capsule, trabeculae and, in particular, the sinuses were strongly supported by reticular fibres and cells. The morphology of these nodes displayed similarity to that of other ruminant species.

Histology of hemal nodes of the water buffalo (Bos bubalus)

Hemal nodes are independent lymphoid organs found in various mammals but are ignored by most immunologists. They seem to play a role in defense against blood-borne infections in some species. The structure of the hemal node has been described in various species but, so far, not in the water buffalo. Specimens were obtained from ten clinically healthy male animals (five calves: 2-3 months old; five bulls: 2-8 years old). Six hemal nodes were obtained from each animal from the mesenteric and perirectal region. The samples were studied by light and transmission electron microscopy. The hemal nodes are bean-shaped or spherical, with one hilus through which the hilus arteries and nerves enter the node and from which veins and lymphatics leave it. The buffalo hemal node has a thin capsule of connective tissue and a few smooth muscle cells. Trabeculae extend from the capsule partially dividing the parenchyma. Subcapsular and trabecular blood sinuses are present. The parenchyma is composed of irregular lymphoid cords rich in erythrocytes, macrophages, and plasma cells and is separated by blood sinuses of variable size engorged with blood. These blood sinuses drain into the trabecular sinuses and then into the subcapsular sinus. In calves, the size of the lymphoid cords is larger than that in adult bulls. Buffalo hemal nodes can be classified as typical hemal nodes, because they are definitely different from hemolymph nodes in other species. They may play a role in filtering the blood.

Magnetic resonance imaging technique for the examination of canine mammary tumours

The aim of this study was to adapt the human magnetic resonance imaging (MRI) sequences for use in the routine examination of canine mammary glands. MRI was performed on 10, middle- to old-aged dogs of different breeds. It was found that T1- and T2-weighted spin echo, short T1 inversion recovery sequences and a gradient echo (GE) dynamic T1-weighted measurement made in the coronal and transversal planes were the most informative MR diagnostic methods for imaging canine mammary tumours. The static MR technique is the most detailed imaging modality for differentiating the tissue types in the substance of the mammary gland. The MRI findings were in close relationship with the histological result (five malignant mixed tumours and five cases of invasive ductal carcinoma). Using the GE dynamic contrast-enhanced sequence the morphological patterns as well as the kinetic parameters proved to be malignant. By the dynamic measurement technique initial information was obtained on the contrast enhancing properties, which are valuable factors during in vivo staging and in the prognostic work.