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Spleen Microcirculation
Published in John H. Barker, Gary L. Anderson, Michael D. Menger, Clinically Applied Microcirculation Research, 2019
Alan C. Groom, Eric E. Schmidt, Ian C. MacDonald
The nature of microcirculatory pathways bordering the white pulp has received little attention and is not included in Figure 2 or in standard histology texts. The clearest evidence has come from microvascular corrosion casts and will be discussed here for the normal human spleen (for details see Schmidt et al., Reference 4). The interrelationship between lymphatic nodules and surrounding vascular structures may be seen in Figure 3. Directly bordering the lymphatic nodule is the marginal sinus. This consists of a series of thin anastomosing vascular spaces, receiving a plentiful blood supply from capillaries that terminate on its outward face (not visible in Figure 3). Blood flows circumferentially through the marginal sinus before moving radially outward (via apertures in its outer wall) to the surrounding marginal zone, a finely meshed reticulum up to 200 µm thick. Beyond the marginal zone lies the extensive reticular meshwork of the red pulp.
The Lymphoid System
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Three components of the splenic white matter that may be confusing when comparing species include the mantle zone or corona, the marginal sinus, and the MZ. The mantle zone is a ring of darkly staining small lymphocytes that surround the germinal centers of secondary follicles in dogs, nonhuman primates, and humans (Sternberg 1997), whereas in the rat the mantle zone is poorly identifiable or lacking, and as a result is often not mentioned in the rodent literature (Figure 16.6a). In those species that have one, the mantle zone is then surrounded by the medium-sized lymphocytes of the MZ (Figure 16.6c). In rats, the follicle is separated from the MZ by a distinct marginal sinus. A marginal sinus is not visible in humans, mice, dogs, or nonhuman primates by standard microscopy (Cesta 2006b; Han et al. 1997). In contrast to nomenclature for rodents, the term MZ is used in man to describe a specific and unique splenic structure that is always around small IgD+ and IgM+ lymphocytes of the mantle zone secondary or primary follicles (Han et al. 1997). In addition, the T-cell areas of man are not as regularly arranged around arterioles as they are in rodents, but are instead irregular areas containing small, polymorphic T-helper/inducer lymphocytes.
Development and anatomy of the venous system
Published in Peter Gloviczki, Michael C. Dalsing, Bo Eklöf, Fedor Lurie, Thomas W. Wakefield, Monika L. Gloviczki, Handbook of Venous and Lymphatic Disorders, 2017
The axial artery of the upper limb forms the brachial artery in the arm and the interosseous artery in the forearm, with the ulnar and radial arteries forming later. As the digits are forming, the apical marginal sinus regresses, but the proximal marginal channels persist as the cephalic and basilic veins.
The role of sialic acid-binding immunoglobulin-like-lectin-1 (siglec-1) in immunology and infectious disease
Published in International Reviews of Immunology, 2023
Shane Prenzler, Santosh Rudrawar, Mario Waespy, Sørge Kelm, Shailendra Anoopkumar-Dukie, Thomas Haselhorst
The potential for utilizing Siglec-1’s function in the context of vaccine development has been proposed due to the specificity of Siglec-1 designated antigen presenting cells like that of macrophages located in close proximity to invariant natural killer T (iNKT) cells, CD4+ T-cells, CD8+ T-cells and B-cells [123–128]. Areas where interactions occur between CD169+ macrophages and various lymphocytes include the lymph nodes and the spleen [129, 130]. The primary model to study these interactions is the murine mouse model, which presents some obstacles [131, 132]. Despite several studies which have investigated the ability of CD169+ macrophages being able to influence nearby lymphocytes, it has not yet been proven that CD169+ macrophages play a role in cross-presentation to human CD8+ T-cells in vivo [128, 133]. Furthermore, the microanatomy of the spleen differs between that of mice and humans with regard to the location of CD169+ macrophages [131, 132]. In murine models, CD169+ macrophages are located in the marginal zone of the spleen, which lines the marginal sinus and are able to capture blood-borne pathogens before and interact with other immune cells [131]. The analogous location of splenic human CD169+ macrophages would be at the ends of capillary sheaths in the perifollicular area which mice lack [132]. Despite the anatomical differences, human CD169+ macrophages at the ends of these capillary sheaths are hypothesized to be able to also interact and capture blood-borne pathogens as do those in murine models [128]. The population of CD169+ macrophages in the lymph node sinuses of humans and mice seem similar [129].
Unique variant of idiopathic intracranial hypertension dural sinus stenting
Published in International Journal of Neuroscience, 2021
Anthony M. Alvarado, Praneeta Nalluri, Andrew M. Alvarado, Alan Reeves, Michael G. Abraham
A 55-year-old female presented with a 9-month history of headaches and decreased vision. Initial ophthalmologic evaluation demonstrated bilateral optic disc edema with bilateral inferior arcuate defects and Diamox treatment was subsequently initiated. Cerebral imaging revealed bilateral hypoplastic transverse-sigmoid sinuses with a persistent occipital-marginal sinus (POMS). Successive lumbar punctures (LP) demonstrated opening pressures of 31 and 38 cmH2O with the patient obtaining temporary symptom relief. Cerebral venography demonstrated multiple enlarged arachnoid granulations within the POMS resulting in focal stenosis and a mean pressure gradient of18 mmHg (Figures 1 and 2). Venography also demonstrated dominant drainage through the POMS. Given the patient received minimal improvement with Diamox therapy, endovascular treatment in the form of venous sinus stenting of the POMS was recommended [3].
Considering the spleen in sickle cell disease
Published in Expert Review of Hematology, 2019
Sara El Hoss, Valentine Brousse
One reason why such important questions have remained unanswered pertains to the major differences between human and animal spleens. In fact, very few animal models may allow splenic investigations that can be unequivocally extrapolated to the human spleen. Many mammals do not have a sinusal spleen or have a spleen that serves additional functions, like a storage function. Horses, for example, rely on their ability to increase significantly their hematocrit, and thus, the oxygen-carrying capacity of the circulation following spleen contraction during effort [4]. Importantly, the spleen in rodents presents very important structural and functional differences [8]. For instance, the white pulp is prominent in rodents, and its composition is different: both the number of follicles and the extent of periarteriolar lymphocytes sheaths in rats are much higher than in humans. A marginal zone and a marginal sinus (a vascular channel around the marginal zone) are both described in rodents but not in human. Another difference pertains to the phenotype of the sinus lining endothelial cells that are species-specific (and also unique regarding other human endothelial cells). Last but not least, the spleen in mice has an erythropoietic function which inevitably leads to major differences particularly when pathologic changes take place, as in SCD.