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Science Immunology Mar 2019The spleen is the largest secondary lymphoid organ in the body and, as such, hosts a wide range of immunologic functions alongside its roles in hematopoiesis and red... (Review)
Review
The spleen is the largest secondary lymphoid organ in the body and, as such, hosts a wide range of immunologic functions alongside its roles in hematopoiesis and red blood cell clearance. The physical organization of the spleen allows it to filter blood of pathogens and abnormal cells and facilitate low-probability interactions between antigen-presenting cells (APCs) and cognate lymphocytes. APCs specific to the spleen regulate the T and B cell response to these antigenic targets in the blood. This review will focus on cell types, cell organization, and immunologic functions specific to the spleen and how these affect initiation of adaptive immunity to systemic blood-borne antigens. Potential differences in structure and function between mouse and human spleen will also be discussed.
Topics: Adaptive Immunity; Animals; Humans; Lymphocytes; Spleen
PubMed: 30824527
DOI: 10.1126/sciimmunol.aau6085 -
Immunology Jul 2015The microanatomical structure of the spleen has been primarily described in mice and rats. This leads to terminological problems with respect to humans and their... (Review)
Review
The microanatomical structure of the spleen has been primarily described in mice and rats. This leads to terminological problems with respect to humans and their species-specific splenic microstructure. In mice, rats and humans the spleen consists of the white pulp embedded in the red pulp. In the white pulp, T and B lymphocytes form accumulations, the periarteriolar lymphatic sheaths and the follicles, located around intermediate-sized arterial vessels, the central arteries. The red pulp is a reticular connective tissue containing all types of blood cells. The spleen of mice and rats exhibits an additional well-delineated B-cell compartment, the marginal zone, between white and red pulp. This area is, however, absent in human spleen. Human splenic secondary follicles comprise three zones: a germinal centre, a mantle zone and a superficial zone. In humans, arterioles and sheathed capillaries in the red pulp are surrounded by lymphocytes, especially by B cells. Human sheathed capillaries are related to the splenic ellipsoids of most other vertebrates. Such vessels are lacking in rats or mice, which form an evolutionary exception. Capillary sheaths are composed of endothelial cells, pericytes, special stromal sheath cells, macrophages and B lymphocytes. Human spleens most probably host a totally open circulation system, as connections from capillaries to sinuses were not found in the red pulp. Three stromal cell types of different phenotype and location occur in the human white pulp. Splenic white and red pulp structure is reviewed in rats, mice and humans to encourage further investigations on lymphocyte recirculation through the spleen.
Topics: Anatomy, Comparative; Animals; B-Lymphocytes; Capillaries; Cell Movement; Humans; Mice; Models, Anatomic; Rats; Spleen
PubMed: 25827019
DOI: 10.1111/imm.12469 -
Seminars in Hematology Jan 2000In this review, our knowledge concerning the structure and function of the spleen is summarized. The unique architecture of the spleen allows for interactions between... (Review)
Review
In this review, our knowledge concerning the structure and function of the spleen is summarized. The unique architecture of the spleen allows for interactions between the circulatory, reticuloendothelial, and immune systems. Based on these interactions in conjunction with its microanatomy, the spleen is able to maintain the integrity of the blood and respond to circulating antigens. However, this can be a double-edged sword in the case of patients suffering from autoimmune diseases such as immune thrombocytopenic purpura since the spleen can be the site of both antibody production and circulating cell destruction.
Topics: Animals; Humans; Spleen
PubMed: 10676919
DOI: 10.1016/s0037-1963(00)90113-6 -
Radiologia 2019In imaging studies, some developmental anomalies such as perisplenic accessory spleen are easily recognizable due to their high incidence. However, other, less common... (Review)
Review
In imaging studies, some developmental anomalies such as perisplenic accessory spleen are easily recognizable due to their high incidence. However, other, less common anomalies such as intrapancreatic accessory spleen, splenopancreatic fusion, splenogonadal fusion, heterotaxy, and wandering spleen, as well as acquired conditions such as splenosis, can pose diagnostic difficulties. This aim of this review is to show the imaging diagnosis and differential diagnoses of these uncommon splenic anomalies.
Topics: Adult; Aged; Female; Humans; Male; Middle Aged; Spleen
PubMed: 30087001
DOI: 10.1016/j.rx.2018.07.002 -
Annals of Surgery Mar 1994
Topics: Humans; Infections; Spleen; Splenectomy
PubMed: 8147603
DOI: 10.1097/00000658-199403000-00001 -
Digestion 2021Before the discovery of immunological and haematological functions of the spleen, it had for centuries been considered to be a digestive organ of variable size with a... (Review)
Review
BACKGROUND
Before the discovery of immunological and haematological functions of the spleen, it had for centuries been considered to be a digestive organ of variable size with a role in the portal vein system and nutritional metabolism. In the 19th and 20th centuries, volume changes in the spleen related to nutrition were studied using plethysmographic measurements. Rhythmical and regulatory functions of the spleen were demonstrated in the haemodynamics of the splanchnic region and were described as a "hepatolienal pendulum," a "Windkessel function," or a "pressure compensation." These studies were mainly published in German-speaking countries and have not, as far as is known, been discussed in the English-speaking world so far.
SUMMARY
This review explores the historical development of the rhythmical regulatory function of the spleen in the splanchnic region. Older studies and results are followed up in the modern literature, wherever possible, up to the present. The clinical relevance is illustrated with portal hypertension (with congestive or hyperdynamic splenomegaly), coeliac disease, and chronic inflammatory bowel diseases (with functional hyposplenism). Key Message: The spleen's rhythmical regulatory function in nutrition is based on an autonomous rhythm comprising cycles of contractions and dilations of the spleen of around 1 min. These cycles can be influenced by sympathetically mediated single contractions with a release of pooled blood or by portal vein congestion. After food ingestion, the spleen responds either with contraction according to a vasomotor reaction or postprandial congestion with significant increases in volume. The spleen's rhythmical function is lost in the clinical picture of portal hypertension or in coeliac disease and chronic inflammatory bowel diseases. In the aforementioned gastrointestinal diseases, we recommend taking more account of the haemodynamics between the spleen, liver, and intestine. New innovative techniques for recording splenograms are required which, besides elastographic measurements of spleen stiffness, could offer an important tool for early detection, diagnosis, and therapeutic evaluation.
Topics: Humans; Hypertension, Portal; Portal Vein; Spleen; Splenomegaly
PubMed: 32408299
DOI: 10.1159/000507346 -
Sultan Qaboos University Medical Journal Nov 2020Anatomical knowledge regarding the external morphology of the spleen is essential for surgical intervention and radiological diagnosis. A characteristic feature of the...
OBJECTIVES
Anatomical knowledge regarding the external morphology of the spleen is essential for surgical intervention and radiological diagnosis. A characteristic feature of the spleen is the presence of splenic notches at the superior border; however, such notches rarely extend deep enough to be considered fissures or to separate the spleen into multiple lobes. To date, there are very few cadaveric reports of splenic fissures. This study aimed to examine the anatomy and morphological structure of spleens collected from cadavers in order to identify the prevalence and clinical significance of splenic notches, fissures and lobation.
METHODS
This study was conducted at the Department of Anatomy, Katuri Medical College and Hospital, Guntur, Andhra Pradesh, India. A total of 50 spleens were collected from cadavers over a period of seven years from 2012-2019 and examined to determine the presence of splenic notches or fissures.
RESULTS
Of the 50 spleens, 40% had notches at the superior border, 10% had notches at the inferior border and 50% had no notches at either border. Fissures were present in five spleens (10%); of these, three showed incomplete fissures and the remaining two had complete fissures that divided the spleen into two lobes.
CONCLUSION
The findings of this study provide valuable information regarding the anatomy and prevalence of splenic fissures and bilobed spleens. A bilobed spleen is a rare congenital malformation which should be considered distinct from other known splenic anomalies. The presence of splenic fissures in bilobed spleens can serve as a guide for surgeons during conservatory splenectomy procedures.
Topics: Cadaver; Educational Status; Humans; Radiography; Spleen; Splenectomy
PubMed: 33414940
DOI: 10.18295/squmj.2020.20.04.011 -
Veterinary Pathology Jan 2017Splenitis is uncommonly reported in dogs. Herein, the authors describe its prevalence, clinical findings and outcomes, histologic patterns, and causes. Splenic samples...
Splenitis is uncommonly reported in dogs. Herein, the authors describe its prevalence, clinical findings and outcomes, histologic patterns, and causes. Splenic samples of dogs diagnosed with splenitis between 2005 and 2013 were collected and stained with hematoxylin and eosin, Gram, green-Gram, Giemsa, periodic acid-Schiff, and Ziehl-Neelsen. Samples were processed for polymerase chain reaction (PCR) to detect bacteria, fungi, and protozoa ( Leishmania infantum, Hepatozoon canis). Thirty-three of 660 splenic samples (5%) had splenitis. Clinical findings and outcomes were available in 19 dogs (58%); 49% had weakness, 33% had fever, and 84% survived. The most frequent inflammatory patterns included purulent splenitis (27%), pyogranulomatous splenitis (24%), and neutrophilic perisplenitis (15%). One dog had a putative diagnosis of primary splenitis; in 8 dogs, microorganisms were identified histologically or by PCR in the spleen without obvious comorbidities. Twenty-four dogs (73%) had concurrent diseases; a permissive role in the development of splenitis was suspected in 21 of these cases. Histologic examination identified the cause of splenitis in 10 dogs. Bacteria were identified by PCR in 23 cases, but the bacteria were confirmed histologically in only 6 of these. Leishmania was detected with PCR in 6 dogs. Leishmania was identified in 1 dog and H. canis in another histologically, but both were PCR negative. Fungi were identified in 8 spleens by PCR and in 1 by histology. This study suggests that splenitis is uncommon in dogs and is frequently associated with systemic diseases. Prognosis is favorable in most cases. Identification of bacteria, fungi, and protozoa in the spleens of affected dogs with PCR should be interpreted cautiously, because the findings are not confirmed histologically in many cases.
Topics: Animals; Biopsy; Dog Diseases; Dogs; Male; Polymerase Chain Reaction; Spleen; Splenic Diseases
PubMed: 27337982
DOI: 10.1177/0300985816653989 -
Anatomia, Histologia, Embryologia Jul 2019Spleen is one of the important lymphoid organs with wide variations of morphological and physiological functions according to species. Morphology and function of the...
Spleen is one of the important lymphoid organs with wide variations of morphological and physiological functions according to species. Morphology and function of the spleen in bats, which are hosts to several viral strains without exhibiting clinical symptoms, remain to be fully elucidated. This study aims to examine the spleen morphology of fruit bats associated with their physiological functions. Spleen histological observations were performed in three fruit bats species: Cynopterus titthaecheilus (n = 9), Rousettus leschenaultii (n = 3) and Pteropus vampyrus (n = 3). The spleens of these fruit bats were surrounded by a thin capsule. Red pulp consisted of splenic cord and wide vascular space filled with blood. Ellipsoids in all three studied species were found numerously and adjacent to one another forming macrophages aggregates. White pulp consisted of periarteriolar lymphoid sheaths (PALS), lymphoid follicles and marginal zone. The lymphoid follicle contained a germinal centre and a tingible body macrophage that might reflect an active immune system. The marginal zone was prominent and well developed. This study reports some differences in spleen structure of fruit bats compared to other bat species previously reported and discusses possible physiological implications of the spleen based on its morphology.
Topics: Animals; Chiroptera; Spleen
PubMed: 30968443
DOI: 10.1111/ahe.12442 -
Journal of Nuclear Medicine Technology Mar 2022A congenital abnormal connection between an accessory spleen and a gonad is called splenogonadal fusion. The parent of a 3-y-old boy brought him to King Saud Medical...
A congenital abnormal connection between an accessory spleen and a gonad is called splenogonadal fusion. The parent of a 3-y-old boy brought him to King Saud Medical City because he had left scrotal swelling that had begun 1 y previously. Tc-sulfur colloid (SC) imaging has superior sensitivity and specificity in targeting the liver, spleen, and bone marrow, in that these are the only organs that Tc-SC can visualize. Furthermore, if these tissues appear anywhere other than their usual locations, such as in the case of an accessory spleen, Tc-SC imaging can identify them even without biopsy or-in the case of splenogonadal fusion-orchiectomy. In the current case, the patient underwent laparoscopy, the masses were removed, and orchiectomy was avoided. Histopathologic examination confirmed normal splenic tissue, matching the imaging results.
Topics: Colloids; Humans; Liver; Male; Single Photon Emission Computed Tomography Computed Tomography; Spleen; Sulfur; Technetium Tc 99m Sulfur Colloid
PubMed: 34750231
DOI: 10.2967/jnmt.121.262233