Spleen anatomy, function and development

Abstract

The spleen, the largest lymphatic organ of the body, is located in the left hypocondrium (Clemente 1984; Skandalakis et al. 2004). In the fifth week of gestation, clusters of mesenchymal cells arise in the left side of the dorsal mesogastrium. They enlarge, undergo vascularization, and fuse to constitute a lobulated primitive spleen covered by the primitive coelomic epithelium. Mesenchymal cells give rise to the capsule and trabecular network of the spleen; the coelomic epithelium provides the serosal peritoneal covering of the spleen (Clemente 1984; Skandalakis et al. 2004). Fetal lobulation are lost late in the fetal period but some indentations, or even clefts and lobulations may persist after birth. Moreover, entrapment of the serosa between mesenchymal clusters may give rise to coelomic cysts (Clemente 1984; Skandalakis et al. 2004). During the rotation of the stomach, to which the dorsal mesogastrium is attached, the spleen is shifted to the left and rests between the stomach anteriorly, and the left kidney and the tail of the pancreas posteriorly. The portion of the dorsal mesogastrium between the stomach and the spleen will give rise to the gastrosplenic ligament, whereas the partially reabsorbed posterior portion of the dorsal mesogastrium will form the splenorenal and splenopancreatic ligaments (Clemente 1984; Skandalakis et al. 2004). The mesogastrium covering the spleen will give rise to its serosal capsule, a portion of which firmly attaches to the dorsal mesogastrium covering part of the upper left kidney to constitute the bare area of the spleen, posterior to which ascites cannot accumulate (Mathieson and Cooperberg 1998).