Spleen – Tutorial

Please read Unit 8 – Introduction to Lymphatic System Tissues prior to completing the activities in this chapter.

Introduction to the Spleen

The spleen is a lymphatic system organ approximately five inches in length located along the lateral border of the greater curvature of the stomach.  Although the spleen is in the abdominal cavity, the inferior ribs on the left side of the body partially protect the soft and highly vascularized tissue of the spleen from blunt trauma.  The spleen is essentially like a giant lymph node for blood as it performs similar functions for circulating blood as lymph nodes do for lymphatic fluid such as monitoring blood for foreign antigens (immune surveillance) and removing abnormal red blood cells and other cellular debris from circulation.

The spleen is a soft, somewhat fragile organ surrounded by a flexible connective tissue capsule comprised of collagen and elastic fibers.  As in lymph nodes, some connective tissue extends from the outer capsule into the interior of the spleen forming partial septa known as trabeculae.  Two types of tissue known as red pulp and white pulp make up the bulk of splenic tissue and are visibly distinct when observed under magnification.  Red pulp, which consists of blood sinuses and irregular arrangements of lymphocytes and macrophages held loosely in place by reticular fibers, makes up the majority of the spleen.  Scattered throughout the red pulp are small regions of white pulp which are areas of highly concentrated lymphocytes.

White pulp of the spleen is found in two distinct forms known as splenic follicles and periarterial lymphatic sheaths.  Splenic follicles are spherical structures containing concentrations of lymphocytes that appear similar to follicles found in the cortex of lymph nodes.  At the center of each splenic follicle is a germinal center containing concentrations of rapidly proliferating (dividing) B-lymphocytes.  Periarterial lymphatic sheaths are dense masses of T-lymphocytes surrounding arteriole blood supply networks that serve as sites where T-lymphocytes can surveil and respond to antigens circulating in the bloodstream.

Tutorial:  Use the image slider below to learn more about the structure and characteristics of the spleen. 

Microscopy:  Use the image slider below to learn how to use a microscope to study the spleen on a microscope slide.

Tutorial:  Use the hotspot image below to learn more about the structure and characteristics of the spleen.   

Tutorial:  Use the image slider below to study numerous examples of tissue from the spleen.