Structure of the spleen of the sea bass (Dicentrarchus labrax): A light and electron microscopic study

The spleen of sea bass (Dicentrarchus labrax) is composed mainly of red pulp, whereas the white pulp is poorly developed. The red pulp consists of clear reticular cells intermingled with blood cells, sinusoids, and melanomacrophage centers (MMCs). The MMCs are enclosed by an interrupted connective tissue capsule and show some areas in continuity with the adjacent pulp. The MMCs are formed by the association of free macrophages that have phagocytosed some blood cells. Sparse white pulp is diffuse, forming a cuff around the pulp arteries and MMCs, or occurring in small groups between the splenic cords. A longitudinal artery and vein, lying side by side, extend the length of the spleen. Frequently the capillaries are surrounded by a sheath of macrophages or ellipsoids. These macrophages may contain erythrocytes in varying degrees of degradation. Lymphopoiesis and plasmapoiesis occur in the sparse lymphold areas. Abundant plasma cell groups may indicate the presence of antibody production.     

An ultrastructural study of the spleen of the ranid frog Rana perezi

The spleen of Rana perezi is encapsulated by connective tissue and shows by light microscopy two areas with no obvious border: the white pulp and the red pulp. The white pulp-lymphoid clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp displays two different portions. The predominant region consists of reticular cells, lymphocytes, a variety of other leucocytes, and cells undergoing division. This area possibly performs a haemopoietic function. The smaller portion of the red pulp is characterized by reticular-phagocytic cells and may be haemocaretic in its function. Macrophages and pigmented cells occur in both white and red pulp. The organization of the spleen of R. perezi can be considered as a transitional or intermediate state between the primitive condition seen in certain fishes and amphibians and the more complex organ of ammiotes.     

Structure and histochemical organization of the spleen of Agama stellio (Sauria: Agamidae) and Chalcides ocellatus (Sauria: Scincidae)

The spleen of Agama stellio is composed mainly of red pulp; the white pulp is poorly developed, and its clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp consists of clear reticular cells intermingled with blood cells, sinusoids, and pigment cells. The spleen of Chalcides ocellatus is encapsulated by connective tissue and is composed of white and red pulp. The white pulp consists of lymphoid tissue that surrounds the central arterioles, forming the periarteriolar lymphocyte sheath (PALS). The red pulp is composed of a system of venous sinuses and cords. The results of various histochemical procedures designed to demonstrate mucosubstances, proteins, and nucleic acids indicate that the spleen in these species resembles the mammalian spleen. © 1993 Wiley-Liss, Inc.     

The architecture of the spleen of the yellow-bellied toad, Bombina variegata

The spleen of the yellow-bellied toad, Bombina variegata , consists of distinct white and red pulps. The well-developed white pulp is formed by a large central lymphocytic region around the numerous blood vessels and by its smaller peripheral ramifications, both surrounded by the more or less developed connective tissue boundary layer. Large peripheral sinuses of the white pulp, filled mostly with lymphocytes, are usually present at the inner side of this boundary. At the outer side of the boundary layer, the lymphocytic marginal zone is often observed. This zone merges into the erythrocyte-rich red pulp formed by cellular cords and small venous sinusoids.
The structure of the spleen of Bombina variegata differs considerably from the spleens of other anuran species studied so far. The highly developed white pulp and its distinct separation from the red pulp may be connected with the important role of the spleen as the main secondary lymphoid organ of B. variegata. The splenic compartmentalization makes the yellow-bellied toads a useful model for experimental immunobiological studies.     

Macrophages and Reticulum Cells in the Spleen of the Dogfish,Scyliorhinus canicula

The presence and ultrastructural features of reticulum cells and macrophages were studied in the spleen of the dogfish Scyliorhinus canicula. Three morphologically distinguishable regions of the spleen were identified: the white pulp, the red pulp and the ellipsoids. In all three, the splenic parenchyma was a meshwork supported by reticulum cells and fibres. Reticulum cells in both the white and the red pulp are irregular elements, the processes of which are joined by cell junctions and embrace developing reticular fibres. The ellipsoids of the dogfish spleen are terminal branches of the splenic arteries of the white pulp, with a sheath consisting of reticulum cells, reticular fibres, ground substance, macrophages and occasional lymphocytes. Isolated melanomacrophages also occur in the ellipsoid walls as well as in the red pulp. In both the white and the red pulp phagocytic reticulum cells, and macrophages appear frequently forming cell associations with surrounding blood cells, mainly lymphocytes. The functional significance of the ellipsoids and the cell-cell clusters of the white and the red pulp is discussed in relation to the immune capacities demonstrated in elasmobranchs.     

Histological, histochemical, and fine structural observations on the spleen of seals

Spleens of three species of Antarctic seals with different diving habits (Weddell seal, crabeater seal, and fur seal) have been studied with histological, histochemical, and electron microscopic methods. The spleens can be classified as nonsinusoidal, with capsule and trabeculae rich in innervated smooth muscle cells. The trabecular system is particularly well developed in the deep- and long-diving Weddell seal. As in other mammals the pulp can be divided into white and red pulp. In the white pulp, periarteriolar lymphatic sheaths and secondary lymphatic nodules occur; both are surrounded by a marginal zone rich in macrophages and eosinophils. The nodules can be observed frequently, which is in accordance with abundance of plasma cells in the red pulp. Well-developed white pulp and numerous plasma cells and eosinophils obviously reflect a high load of nematodes, which have mainly been found in lung and stomach. Additionally, in the red pulp morphological evidence for the following functions has been found: destruction of erythrocytes, erythropoiesis, and thrombopoiesis. In respect to blood flow through the red pulp, we interpret our observations in the following way: terminal branches of arterioles open into the space between the fibroblastic reticulum cells; blood draining from here is collected into pulp veins, which are mainly found near the trabeculae. Thus, the seals have an open vascular compartment in their spleens, as also occurs in the cat. The red pulp is innervated by numerous nerve fibers that seem to include both cholinergic and adrenergic ones. The target cells of these fibers seem to be the fibroblastic reticulum cells, whose state of contraction may influence the direction of blood flow through the red pulp.     

中华花龟五种器官组织学观察

利用石蜡切片法对中华花龟的心脏、肝脏、脾脏、肺和肾脏等组织器官进行了组织学观察.结果显示心肌的特点是暗带较窄,心肌纤维束状排列.肝脏分3叶,肝实质内结缔组织少,肝小叶分界不清楚.脾脏分被膜和实质两部分,实质由白髓和红髓构成,白髓包括椭球周围淋巴鞘(PELS)和动脉周围淋巴鞘(PALS),红髓由脾索和脾窦组成,未发现淋巴小结和生发中心.肺一对,为长形扁平囊,肺泡囊状,肺泡内可见管壁的结节状膨大.肾脏由肾小体、颈段、近曲小管、中间段、远曲小管和收集管6部分构成,肾小体由肾小球和肾小囊组成,在肾小体附近可见致密斑样结构.     

Light microscopic study of the alligator (Alligator mississippiensis) spleen with special reference to vascular architecture

The spleen of the American alligator (Alligator mississippiensis) was studied histologically. The alligator spleen is a bean-shaped organ covered by a thick capsule. The concave side of the spleen faces the pancreas. Many venous vessels are present in the capsule. The stem segment of a large intestinal artery, the lieno-intestinal artery, enters the organ from its upper pole, runs within the organ at the axial center (axial artery) and leaves it from the lower pole. Many peripheral branches originate from the axial artery towards the capsule, but the artery has no associated collateral veins. The capsule/trabecula and white and red pulp may be distinguished. The capsular veins appear to be continuous with venous vessels that sheathe the axial artery and its peripheral branches. Surrounding the axial artery are trabeculae containing leiomyocytes and nerves. The white pulp consists of lymphoid tissue and occurs around terminal arterioles and sheathed capillaries. The materials examined do not show germinal centers. The large red pulp is composed of venous vessels and splenic cords rich in reticular fibers. Two venous routes, hilar and capsular, are present. The structural characteristics of the alligator spleen are similar to spleens of other reptiles; however, its vascular architecture is primitive, suggesting that the alligator spleen may be a portal spleen. J Morphol 233:43–52, 1997. © 1997 Wiley-Liss, Inc.     

Phagocytosis in the spleen of the sunfish Lepomis spp.

A histological investigation of the filtering function of the spleen of the sunfish Lepomis spp. was conducted by light, scanning, and transmission electron microscopy. The parenchyma of the organ is predominantly red pulp, a system of splenic cords and sinuses. The white pulp consists of loose lymphoid tissue which forms a cuff around the pulp arteries. Filtering of particulate matter from the blood occurs in the red pulp by phagocytes of the pulp cords and ellipsoids (periarterial macrophage sheaths). The ellipsoids are pale-staining cuffs of macrophages and reticular cells in a framework of reticular fibres surrounding the arterial capillaries. Destruction of effete blood cells (especially erythrocytes) is confined to the pigment nodules; particulate matter is not taken up by the nodules. These yellow-brown bodies are dispersed throughout the red pulp and are bounded by a reticular capsule. They contain masses of phagocytes and have the appearance of a morula. They are associated with blood vessels and are surrounded by sinusoids. Prussian Blue stain shows the presence of haemosiderin within their phagocytes. The phagocytes of the pigment nodules are filled with inclusions such as residual bodies, siderosomes, and fragments of erythrocytes. The early filtering of particulate matter by the phagocytes of the pulp cords and ellipsoids may allow for a more efficient phagocytosis of erythrocytes by the pigment nodules, followed by storage and reutilization of iron-containing compounds uncontaminated by other phagocytosed material.     

The spleen ofmustelus schmitti (chondrichthyes, triakidae): A light and electron microscopic study

The spleen ofMustelus schmitti is described, being an elongated organ running dorsally along the stomach and surrounded by a thin capsule without muscular tissue. The classical division between red and white pulps was evident, with a marginal sinus surrounding the latter. Numerous ellipsoids were located in the red pulp, inside nodular-like structures, or in the marginal sinus. Two types of reticular cells were apparent as well as macrophages and melanomacrophages. Hemopoiesis was present through immature and mature cells of the erythroid and thrombocytoid lineages, but no evidence of granulopoiesis was found. Comparison amongMustelus species and between chondrichthyan and mammalian spleens are made.     

Intravital-microscopic observations on the intravascular behavior of blood cell components during dietary-induced hyperlipidemia in the male rabbit

In normal male rabbits loaded dietary cholesterol, intravital-microscopy revealed a marked acceleration of intravascular adhesiveness of white blood cells and aggregability of red blood cells and a swarming of lipid-laden macrophages in connective tissue space concurrently with a systemic hyperlipidemia and anemia. Possible roles of the microcirculatory changes in the atherogenesis were discussed.     

Immune proteasomes in the developing rat spleen

Changes in the structure of the rat spleen and the distribution of immune proteasomes in it during early postnatal development have been studied using double immunofluorescent staining of tissue sections with antibodies to the LMP7 immune proteasome subunit and to specific markers of T and B lymphocytes. It has been shown that the white pulp on postnatal day 5 is not yet colonized by lymphocytes and contains a smaller amount of immune proteasomes than the red pulp. At this stage, T and B lymphocytes concentrate mainly in the red pulp. On day 8, B lymphocytes occupy the marginal zone, while T lymphocytes aggregate into dense strands close to the white pulp. By day 18, T lymphocytes form periarteriolar sheaths in the white pulp, and the contents of immune proteasomes in the red and white pulp become equally high. An increase in the total content of immune proteasomes in the spleen on the third postnatal week was revealed in our previous study by Western blotting. In addition to T and B lymphocytes, immune proteasomes have also been revealed in other spleen cell types, probably in macrophages and reticular cells of the white pulp. Thus, the postnatal development of the spleen is associated with an increase in the contents of immune proteasomes in it.     

瓦氏黄颡鱼和岩原鲤脾脏的组织学观察

运用组织学方法对瓦氏黄颡鱼和岩原鲤脾脏的显微结构进行了研究.瓦氏黄颡鱼和岩原鲤脾脏被膜薄,仅由一层单层扁平上皮细胞和结缔组织纤维构成,脾小梁明显,红髓和白髓混合,无明显的分界,鞘毛细血管发达;瓦氏黄颡鱼脾小梁细而少,白髓中淋巴细胞密集,在靠近被膜的脾实质边缘区域密集的淋巴细胞形成外形类似淋巴小结的结构,巨噬细胞聚集形成明显的巨噬细胞中心;岩原鲤脾小梁发达,伸入脾实质将脾脏分隔成一个个的小叶,白髓中密集的淋巴细胞较少,未见类似淋巴小结的结构,巨噬细胞分散存在,无明显的巨噬细胞中心.     

The spleen of the African lungfish Protopterus annectens: freshwater and aestivation

We describe the structure of the spleen of the African lungfish Protopterus annectens in freshwater conditions, and after 6?months of aestivation. The spleen is formed by cortical tissue that surrounds the splenic parenchyma. The cortex is a reticulum that contains two types of granulocytes, developing and mature plasma cells, and melanomacrophage centres (MMCs). The parenchyma is divided into lobules that show a subcapsular sinus and areas of red pulp and white pulp. Red pulp contains vascular sinuses and atypical cords formed by delicate trabeculae. White pulp also contains vascular sinuses and cords. Structural data indicate that red pulp is involved in erythropoiesis, destruction of effete erythrocytes, and plasma cell differentiation. White pulp appears to be involved in the production of immune responses. Macrophages and sinus endothelial cells constitute the reticulo-endothelial system of the spleen. After aestivation, the number of MMCs increases, and spleen tissue is infiltrated by lymphocytes, granulocytes, and monocytes. Also, white pulp is reduced, and sinus endothelial cells undergo vacuolar degeneration. Lungfish spleen shares structural characteristics with secondary lymphoid organs of both ectothermic and endothermic vertebrates, but appears to have evolved in unique ways.     

Ultrastructure of phagocytic cells in the spleen of Psammophis sibilans (serpentes: Colubridae)

The spleen of Psammophis sibilans is composed mainly of red pulp, the white pulp being poorly developed. The white pulp lymphoid clusters are scattered throughout the organ and contain lymphocytes, reticular cells, and some plasma cells. The red pulp consists of reticular cells intermingled with blood cells, sinusoids, and melanomacrophage centers (MMCs). Filtering of particulate matter from the blood occurs in the red pulp by phagocytes of the pulp cord. MMCs are formed by the association of free macrophages that have phagocytosed some blood cells. Early filtering of particulate matter by the phagocytes of the pulp cords may allow for more efficient phagocytosis of erythrocytes by the MMCs. © 1994 Wiley-Liss, Inc.     

A high-fat diet associated with acute schistosomiasis mansoni causes disorganization in splenic architecture in mice

To date, the effect of the changes promoted by hypercholesterolemia and experimental schistosomiasis infection on splenic architecture has remained elusive. In this paper, we compared spleen from control and infected mice fed either high-fat (29% lipids) or standard diet (12% lipids), assessing spleen volume by liquid displacement and splenic disorganization by histopathology, morphometry and stereology. Infected mice showed higher spleen volume than in corresponding uninfected mice (P<0.05). The white pulp compartment was reduced, red pulp and germinal center were enhanced (P<0.01). Microscopic examination showed cellular infiltrates characterized by polymorfonuclear cells, with intensive lymphocytic mitosis and Mott cells. Hemosiderin deposits tended to be in less extent in infected mice compared with uninfected controls. The red pulp compartment showed a significantly (P<0.05) increased average number of megakaryocytes compared with uninfected mice, which may be associated with hematopoietic reconstitution. High-fat fed mice showed larger white pulp than controls (P<0.05). Standard fed mice showed exudative-productive granuloma distributed only sparsely in the red pulp, whereas a tissue reaction characterized by a cell infiltration in high-fat fed mice was found. The results of the present study suggest that there is a significant relationship between high-fat diet intake and splenic disorganization such as a decrease in the numerical density of white pulp and, red pulp and germinal center hyperplasia. Such structural disorganization due to co-morbidites (schistosomiasis and dyslipidemia) may affect the microenvironments of the spleen that are necessary for the generation of immune responses to antigens.     

鲤鱼和鲫鱼脾脏显微结构和亚显微结构的研究

鲤鱼和鲫鱼的脾脏中都没有小梁,其红髓和白髓是混合的。脾脏中都有椭圆体,其末端向脾髓开放。脾髓的纤维网眼中缺乏血管壁,椭圆体毛细血管中的血液可直接流入脾髓网状结缔组织的腔隙中。腹腔注射墨汁的鲫鱼,2小时后即可在椭圆体的巨噬细胞中看到碳粒的积累,可见脾脏的过滤作用主要在椭圆体中进行。在注射墨汁的鲫鱼脾脏中,黑色素巨噬细胞中心比未经注射鱼的脾脏明显,且数量增多,它和哺乳动物淋巴结和脾脏中的生发中心结构和功能都不相同。       

Histopathology of natural Ebola virus subtype Reston infection in cynomolgus macaques during the Philippine outbreak in 1996.

We investigated the livers, spleens, kidneys and lungs collected from 24 cynomolgus macaques (Macaca fascicularis) naturally infected with Ebola virus subtype Reston (EBO-R) during the Philippine outbreak in 1996, in order to reveal the histopathologic findings. These macaques showed necrotic hepatocytes with inclusions, slight to massive fibrin deposition in splenic cords, depletion of lymphoid cells in the white pulp of the spleen, and fibrin thrombi in some organs. Immunohistochemical analysis using anti-leukocyte antigen L1 antibody revealed an increase in blood-derived macrophages/monocytes in the livers, kidneys and lungs of EBO-R infected macaques. EBO-R NP antigens were detected in the macrophages/monocytes, endothelial cells and fibroblasts in the liver, spleen, kidney and lung. These results indicate that EBO-R infection is characterized by systemic coagulopathy and an increase in blood-derived macrophages/monocytes in accordance with the EBO-R propagation in macrophages/monocytes.     

Immune-complex-trapping cells in the spleen of the oriental fire-bellied toad,Bombina orientalis

Summary The spleen of the oriental fire-bellied toad, Bombina orientalis, consists of well-developed white pulp, separated from the lymphocytic marginal zone by the connective tissue boundary layer. Injection of peroxidase-conjugated rabbit anti-peroxidase revealed that these immune complexes were localized on the surface of acid-phosphatase-positive and non-specific-esterasepositive cells in the white pulp. The majority of immunecomplex-trapping cells were present around the blood vessels. Cell processes of some of these cells penetrated into the wall of blood vessels. The significance of the present findings is discussed with respect to the evolution of immune-complex-trapping cells in the spleen.