Cambios

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!colspan="2"|<center>Location canine radiograph</center>

!colspan="2"|<center>Ubicación placa canino</center>

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!Lateral view

!Vista Lateral

!Ventrodorsal view

!Vista Ventrodorsal

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|colspan="2"|<center>^{©Nottingham Uni 2008}</center>

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==Introduction==

==Introducción==

The spleen is a major lymphoid and blood filtration organ and is located in the left cranial abdomen. It is responsible for storing and removing [[Erythrocytes|erythrocytes]] from the blood as well as antigen surveillance of the blood and antibody production.

El bazo es un importante órgano linfoide y  lugar de filtración de la sangre y se localiza en el abdomen craneal izquierdo. Es el responsable del almacenamiento y destrucción de los [[Eritrocitos|eritrocitos]], de los antígenos de vigilancia de la sangre y de anticuerpos.

==Development==

==Desarollo==

<p>The spleen develops in association with the digestive system in the dorsal mesogastrium, and as the [[Monogastric Stomach - Anatomy & Physiology|stomach]] rotates during development the spleen comes to occupy the left cranial abdomen. Haematopoietic cells in the spleen are derived from the AGM (aorta-gonad-mesonephros) and yolk sac and as the [[:Category:Primary Lymphoid Tissue|primary lymphoid organs]] become established it becomes populated with [[Lymphocytes#Types|T and B lymphocytes]].</p>

<p>El bazo se desarrolla en relación con el sistema digestivo en el mesogastrio dorsal, de forma que al rotar el [[Estómago Monogástrico - Anatomía & Fisiología|estómago]] durante el desarrollo, el bazo acaba ocupando la parte izquierda del abdomen craneal. Las células hematopoyéticas del bazo derivan de la AGM (aorta-gónada-mesonefros) y del saco vitelino y tal y como está establecido en los [[:Categoría:Tejido Linfoide Primario|órganos linfoides primarios]] acaba siendo lugar de asiento de grandes poblaciones de [[Linfocitos#Tipos|linfocitos T y B]].</p>

==Structure==

==Estructura==

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|[[Image:LH_Spleen_Equine_Ultrasound.jpg|150px]]

|[[Image:LH_Spleen_Equine_Ultrasound.jpg|150px]]

|colspan="2"|<center>^{©Nottingham Uni 2008}</center>

|colspan="2"|<center>^{©Nottingham Uni 2008}</center>

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<p>The spleen lies vertically on the left side of the cranial abdomen. It is attached to the greater curvature of the [[Alimentary System Overview - Anatomy & Physiology#Stomach|stomach]] by the gastrosplenic ligament. The spleen is enclosed in a capsule of fibrous and elastic tissue that extends into the parenchyma as trabeculae. </p>

<p>El bazo asienta verticalmente en el lado izquierdo del abdomen craneal. Se une a la curvatura mayor del [[Sistema Digestivo - Resumen - Anatomía & Fisiología#Estómago|estómago]] por el ligamento gastroesplénico. Está envuelto en una cápsula de tejido fibroso y elástico que se interna hacia el parénquima formando trabéculas.</p>

<p> The parenchyma is supported by a fine mesh of reticular fibres and is divided into two types of tissue, the red and the white pulp, which are separated by the marginal sinus.</p>

<p> El parénquima es sostenido por una fina malla de fibras reticulares y se divide en dos tipos de tejido, la pulpa roja y la pulpa blanca, que están separados por el seno marginal.</p>

===Red Pulp===

===Pulpa Roja===

<p>The red pulp makes up the majority of the spleen and is composed of a network of cell cords in series with vascular sinuses. The splenic cords contain [[Macrophages|macrophages]], [[B cell differentiation#Plasma cells|plasma cells]], [[Lymphocytes - Introduction|lymphocytes]] and other mature blood cells e.g. [[Blood Cells - Overview|granulocytes]] and [[Erythrocytes|erythrocytes]].  While the vascular sinuses are wide vascular channels lined with endothelial cells. Blood cells and fluid can pass into the splenic cords through fenestrations in the sinus walls. </p>

<p>La pulpa roja constituye la mayor parte del bazo y se compone de una red de cordones celulares con senos vasculares. Los cordones esplénicos contienen [[Macrófagos|macrófagos]], [[Diferenciación de las Células B#Células Plasmáticas|células plasmáticas]], [[Linfocitos - Introducción|linfocitos]] y otras células sanguíneas maduras, como por ejemplo [[Células de Sangre - Resumen|granulocitos]] y [[Eritrocitos|eritrocitos]].  Por otro lado, los senos vasculares son amplios canales vasculares revestidos por células endoteliales. Las células de la sangre y los fluidos pueden pasar a través de los cordones esplénicos a través  de fenestraciones existentes en las paredes de los senos. </p>

===White Pulp===

===Pulpa Blanca===

<p>White pulp is organised in relation to the splenic arterioles and consists of discrete lymphoid tissue surrounding a central arteriole. There is a sheath of [[Lymphocytes#T cells|T cells]] directly around the arteriole, the periarteriolar lymphoid sheath (PALS), which is surrounded by a marginal sinus, and then a zone of [[Lymphocytes#B cells|B cells]] and [[Macrophages|macrophages]] (the marginal zone). B cell follicles are associated with the marginal zone and expand and develop germinal centres after antigen activation. The marginal sinuses are linked to the red pulp sinuses. </p><p>White pulp stains basophilic in a H&E stain</p>

<p>La pulpa blanca se organiza en relación con las arteriolas esplénicas y se compone de tejido linfoide difuso que rodea a una arteriola central. Existe una vaina de [[Linfocitos#Células T|células T]] alrededor de la arteriola, la denominada vaina linfática periarteriolar (PALS), que está rodeada por un seno marginal, y posteriormente por una zona de [[Linfocitos#Células B|células B]] y [[Macrófagos|macrófagos]] (la zona marginal). Los folículos de células B están asociados con la zona marginal y desarrollan y expanden centros germinales tras la activación antigénica. Los senos marginales están vinculados a los senos de la pulpa roja. </p><p>La pulpa blanca aparece basófila en una tinción con H-E.</p>

====Species Differences====

====Diferencias Entre las Especies====

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!Equine

!Equino

!Bovine

!Bovino

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|<center>[[Image:LH_Spleen_Ovine_Photo.jpg|150px]]</center>

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!Canine

!Canino

!Ovine

!Ovino

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<p>The capsule and trabeculae are much more muscular in carnivores and horses than ruminants</p>

<p>La cápsula y las trabéculas son mucho más musculares en los carnívoros y los caballos que en los rumiantes</p>

*Carnivores

*Carnívoros

**Is elongated and dumb-bell shaped (larger ventrally)

**Es alargada y en forma de mancuerna (más grande ventralmente).

*Ruminants

*Rumiantes

**Is flat and oblong shaped

**Es plana y de forma oblongada.

*Horses

*Caballos

**Lies under the last three [[Ribs and Sternum - Anatomy & Physiology|ribs]]. Dorsally it is broad but narrows as it extends cranially and ventrally

**Se encuentra debajo de las tres últimas [[Costillas y Esternón - Anatomía & Fisiología|costillas]]. Dorsalmente es amplia, pero se estrecha a medida que se extiende craneal y ventralmente.

**On rectal palpation it is located against the body wall and feels smooth with a sharp border

**En la palpación rectal se encuentra contra la pared del cuerpo y su textura es suave, con un borde afilado.

*Pigs

*Cerdos

**Elongated and strap-like under the last few [[Ribs and Sternum - Anatomy & Physiology|ribs]]

**Alargada y en forma de cuerda bajo las últimas [[Costillas y Esternón - Anatomía & Fisiología|costillas]]

*Birds ([[Media:Avian Liver and Spleen.jpg|Picture here]])

*Aves ([[Media:Avian Liver and Spleen.jpg|Imagen aquí]])

**Lies alongside, to the right, of the [[Proventriculus - Anatomy & Physiology|proventriculus]] and is found caudodorsally to the [[Avian Liver - Anatomy & Physiology|liver]]

**Se sitúa al lado derecho del [[Proventrículo - Anatomía & Fisiología|proventrículo]] y  se encuentra caudodorsalmente al [[Hígado Aviar - Anatomía & Fisiología|hígado]]

**Spherical in chickens, triangular in ducks & oval in pigeons

**Esférica en los pollos, triangular en patos y de forma ovalada en las palomas.

===Vasculature===

===Vasculatura===

<p>The splenic artery, a branch of the celiac artery, supplies the spleen. The artery branches into arterioles and capillaries, which may either:  

<p>La arteria esplénica, una rama de la arteria celíaca, se encarga de irrigar al bazo. La arteria se divide en arteriolas y capilares, por lo que puede:

*Connect with the venous sinuses, or

*Establecer conexión con los senos venosos, o

*Terminate with open ends in the splenic cords

*Terminar desembocando en los cordones esplénicos

Blood released into the splenic cords, either from the sinuses or capillaries, eventually filters back into the sinus network. The sinuses converge and empty into trabecular veins, which then merge into a single splenic vein which then empties into the portal vein.</p>

La sangre liberada en los cordones esplénicos, ya sea de los senos o de los capilares, eventualmente se filtra de nuevo dentro de la red de senos. Los senos convergen y desembocan en las venas trabeculares, que luego se funden en una sola vena esplénica que desemboca a su vez en la vena porta.</p>

<p>[[Lymphocytes - Introduction|Lymphocytes]] in the arterial blood migrate from the red pulp sinuses, through the splenic cords and through the white pulp. [[Lymphocytes#T cells|T cells]] specifically migrate through the PALS and [[Lymphocytes#B cells|B cells]] specifically migrate through the follicles. Antigen in the blood is filtered by the large numbers of [[Macrophages|macrophages]] in the splenic cords and white pulp.</p>

<p>Los [[Linfocitos - Introducción|linfocitos]] de la sangre arterial migran de los senos de la pulpa roja, a través de los cordones esplénicos y a través de la pulpa blanca. Las  [[Linfocitos#Células T|células T]] migran específicamente a través de las vainas linfoides periarteriolares y las [[Linfocitos#Células B|células B]] lo hacen específicamente a través de los folículos. Los  antígenos que viajan en la sangre son filtrados por el gran número de [[Macrófagos|macrófagos]] presentes en los cordones esplénicos y en la pulpa blanca.</p>

====Species Differences====

====Diferencias Entre las Especies====

<p>The splenic artery:

<p>La arteria esplénica:

*Passes through the spleen without dividing in ruminants

*Pasa a través del bazo sin dividirse en los rumiantes.

*Branches regularly as it passes through the spleen in horses and pigs

*Se ramifica regularmente a su paso a través del bazo en caballos y cerdos.

*Branches before it reaches the spleen in dogs and cats</p>

*Se ramifica antes de alcanzar el bazo en perros y gatos.</p>

===Innervation===

===Inervación===

Innervation is purely sympathetic<ref>{{citation|initiallast = Nance|initialfirst = D.M|finallast = Sanders|finalfirst = V.M|year = 2007|jtitle = Autonomic innervation and regulation of the immune system (1987-2007)|jor = Brain, Behavior, and Immunity|vol = 21(6)|range = 736-745}}</ref> and nerve fibres travel with the artery into the spleen.

La inervación es puramente simpática <ref>{{citation|initiallast = Nance|initialfirst = D.M|finallast = Sanders|finalfirst = V.M|year = 2007|jtitle = Autonomic innervation and regulation of the immune system (1987-2007)|jor = Brain, Behavior, and Immunity|vol = 21(6)|range = 736-745}}</ref> y las fibras nerviosas realizan su recorrido junto a la arteria al interior del bazo.  

===Histology===

===Histología===

<gallery perrow="3">

<gallery perrow="3">

Image:LH_Spleen_Rat_Histology.jpg|<p>'''Gross view (rat)'''</p>^{©RVC 2008}

Image:LH_Spleen_Rat_Histology.jpg|<p>'''Gross view (rat)'''</p>^{©RVC 2008}

Image:LH_Spleen_Mouse_Higher_Histology.jpg|<p>'''Megakaryocyte & macrophages (mouse)'''</p>^{©RVC 2008}</gallery>

Image:LH_Spleen_Mouse_Higher_Histology.jpg|<p>'''Megakaryocyte & macrophages (mouse)'''</p>^{©RVC 2008}</gallery>

==Functions==

==Funciones==

<p>The spleen has a number of functions:

<p>The spleen has a number of functions:

*It filters the blood removing ageing [[Erythrocytes|erythrocytes]] and antigens

*It filters the blood removing ageing [[Erythrocytes|erythrocytes]] and antigens

===Erythrocytes & Platelets===

===Erythrocytes & Platelets===

<p>In the foetus the spleen also has a role in [[Haematopoiesis - Overview|haematopoiesis]] when it becomes the main [[Erythrocytes|erythrocyte]] producing organ during the haematopoietic transitional phase.</p>

<p>In the foetus the spleen also has a role in [[Haematopoiesis - Overview|haematopoiesis]] when it becomes the main [[Erythrocytes|erythrocyte]] producing organ during the haematopoietic transitional phase.</p>

<p>In the developed animal the red pulp is involved in the removal of aged, damaged or abnormal [[Erythrocytes|erythrocytes]] (along with the [[Liver - Anatomy & Physiology|liver]] and [[Bone Marrow - Anatomy & Physiology|bone marrow]]). As [[Erythrocytes|erythrocytes]] age they become less supple and this causes them to become damaged when they pass through the very narrow capillaries of the spleen, after which they are phagocytised by splenic [[Macrophages|macrophages]]. If a splenectomy is performed the number of aged [[Erythrocytes|erythrocytes]] in circulation increases.</p>

<p>In the developed animal the red pulp is involved in the removal of aged, damaged or abnormal [[Erythrocytes|erythrocytes]] (along with the [[Hígado - Anatomía & Fisiología|liver]] and [[Bone Marrow - Anatomía & Fisiología|bone marrow]]). As [[Erythrocytes|erythrocytes]] age they become less supple and this causes them to become damaged when they pass through the very narrow capillaries of the spleen, after which they are phagocytised by splenic [[Macrophages|macrophages]]. If a splenectomy is performed the number of aged [[Erythrocytes|erythrocytes]] in circulation increases.</p>

<p> The red pulp also acts as a storage site for [[Erythrocytes|erythrocytes]]. The degree of storage is variable between species but is particularly notable in horses which, during exercise under sympathetic activity, can contract their spleen to increase the concentration of circulating [[Erythrocytes|erythrocytes]]. In some species such as cats and rodents the red pulp acts as a storage site for [[Thrombocytes|platelets]] and contains [[Thrombopoiesis#Megakaryocyte|megakaryocytes]].</p>

<p> The red pulp also acts as a storage site for [[Erythrocytes|erythrocytes]]. The degree of storage is variable between species but is particularly notable in horses which, during exercise under sympathetic activity, can contract their spleen to increase the concentration of circulating [[Erythrocytes|erythrocytes]]. In some species such as cats and rodents the red pulp acts as a storage site for [[Thrombocytes|platelets]] and contains [[Thrombopoiesis#Megakaryocyte|megakaryocytes]].</p>

==In pathology==

==In pathology==

===Direct pathology===

===Direct pathology===

*Specific spleen pathology can be found [[Spleen - Pathology|here]]

*Specific spleen pathology can be found [[Bazo - Patología|here]]

*[[Neoplasia - Pathology#Acute Undifferentiated Leukaemia|Acute undifferentiated leukaemia]] and [[Neoplasia - Pathology#Lymphoid Neoplasms|lymphoid neoplasms]]

*[[Neoplasia - Patología#Acute Undifferentiated Leukaemia|Acute undifferentiated leukaemia]] and [[Neoplasia - Patología#Lymphoid Neoplasms|lymphoid neoplasms]]

===Changed or affected by===

===Changed or affected by===

*[[Post-Mortem Change - Pathology#Agonal Changes|Post mortem change]]

*[[Post-Mortem Change - Pathology#Agonal Changes|Post mortem change]]