**Spleen in humans**. In humans, the spleen parenchyma consists of numerous lobules in structure and contains the portal vein, arteries, bile ducts, lymphatic and nerve plexuses. Blood vessels do not branch in the lobule, but form multiple anastomoses, which gives it the ability to retain blood circulating inside it in a vicious circle. The lobule has the shape of a biconvex lens. From the upper edge of the lobule the parietal membrane of the stomach grows together, which with its muscular layer is included in the musculature of the organ itself and together with it provides 20% of the total musculature