Histological Features and Functional Zones of the Spleen

The spleen is a vital lymphoid organ involved in immune response and hematological regulation. It consists of two primary functional zones: the white pulp, responsible for immune surveillance, and the red pulp, which filters blood and removes senescent cells.

Histological Features

The spleen is encapsulated by a dense fibrous connective tissue, with trabeculae extending inward. The parenchyma consists of:

• White Pulp: Composed of lymphoid follicles containing B and T lymphocytes, organized around central arterioles.
• Red Pulp: Consists of splenic cords and venous sinuses, facilitating filtration and phagocytosis of aged erythrocytes.

Functional Zones

White Pulp

Responsible for antigen presentation and immune cell activation. Key structures include:

• Periarteriolar lymphoid sheath (PALS) containing T lymphocytes.
• B-cell follicles surrounding germinal centers.

Red Pulp

Facilitates blood filtration and erythrocyte recycling through specialized macrophages. Includes:

• Splenic sinusoids with discontinuous endothelium aiding cell passage.
• Reticular connective tissue rich in phagocytes.

Clinical Significance

The spleen plays a crucial role in immune function, hematopoiesis, and blood filtration. Disorders such as splenomegaly, hypersplenism, and spleen rupture can significantly impact health.