Examine a section of the spleen. Identify

• The capsule and
• Trabeculae and
• Note the overall organization into white pulp and red pulp (Fig. 14-23).

Clinical note: Because its capsule is thin and the blood-filled stroma is very delicate, the spleen is easily ruptured by injury to the abdomen and this is a very serious event that can lead to death from the loss of blood into the abdominal cavity. Pictured to the right is a fatal splenic rupture.

The arterial supply to the white and red pulp is  depicted in the diagram at the lower right. The components are difficult to observe in routine histological preparations, but understand the blood flow from the diagram and text and try to identify the major structures on your slide. (“Open circulation” appears to be much more important than “closed circulation” in humans. Know what these terms mean in the spleen’s vasculature.). Click the image for the expanded view.

What is one unique aspect of the spleen compared to other immune organs?

Let's take a closer look at that blood supply.