Changes

<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, plasma cells, lymphocytes and other mature blood cells e.g. granulocytes and 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>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, plasma cells, lymphocytes and other mature blood cells e.g. granulocytes and 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>

===White Pulp===

===White Pulp===

<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 T-cells directly around the arteriole, the periarteriolar lymphoid sheath (PALS), which is surrounded by a marginal sinus, and then a zone of B-cells and 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 is organised in relation to the splenic arterioles and consists of discrete lymphoid tissue surrounding a central arteriole. There is a sheath of T-cells directly around the arteriole, the periarteriolar lymphoid sheath (PALS), which is surrounded by a marginal sinus, and then a zone of B-cells and 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 basophilc in a H&E stain</p>

====Species Differences====

====Species Differences====

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

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

*Carnivores

*Carnivores

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

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

*Ruminants

*Ruminants

**Is flat and oblong shaped

**Is flat and oblong shaped