Periarteriolar lymphoid sheaths

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Synonyms
Pronunciation
Carnegie stage
Days
Precursor
Gives rise to
Part of

Periarteriolar lymphoid sheaths (PALS) are a component of the white pulp of the spleen. They are primarily composed of T lymphocytes and surround the central arterioles within the spleen. PALS play a crucial role in the immune response by facilitating interactions between antigen-presenting cells and T cells.

Structure

PALS are organized around the central arterioles of the spleen and are part of the white pulp, which also includes lymphoid follicles and the marginal zone. The white pulp is responsible for the immune functions of the spleen, contrasting with the red pulp, which is involved in filtering blood and removing old or damaged red blood cells.

Function

The primary function of PALS is to support the activation and proliferation of T cells in response to antigens. When an antigen is presented by dendritic cells or other antigen-presenting cells, T cells within the PALS can become activated and initiate an immune response. This process is essential for the body's defense against infections and other foreign invaders.

Clinical significance

Alterations in the structure or function of PALS can be indicative of various immunological disorders. For example, in conditions such as splenomegaly, the architecture of the spleen, including the PALS, may be disrupted. Understanding the role of PALS in immune responses can aid in the diagnosis and treatment of such conditions.

See also

• Spleen
• White pulp
• T lymphocytes
• Immune system