White pulp

White pulp
Spleen
Transverse section of a portion of the spleen. (Lymphatic nodule labeled at center right.)
Details
Precursor	mesoderm
Artery	trabecular artery
Vein	trabecular vein
Identifiers
Latin	noduli lymphoidei splenici
TA98	A13.2.01.006
TA2	5176
FMA	62805
Anatomical terminology [edit on Wikidata]

White pulp is a histological designation for regions of the spleen (named because it appears whiter than the surrounding red pulp on cross section), that encompasses approximately 25% of splenic tissue. White pulp consists entirely of lymphoid tissue.

Specifically, the white pulp encompasses several areas with distinct functions:

• The periarteriolar lymphoid sheaths (PALS) are typically associated with the arteriole supply of the spleen; they contain T lymphocytes.
• Lymph follicles with dividing B lymphocytes are located between the PALS and the marginal zone bordering on the red pulp. IgM and IgG2 are produced in this zone. These molecules play a role in opsonization of extracellular organisms, encapsulated bacteria in particular.
• The marginal zone exists between the white pulp and red pulp.^[1] It is located farther away from the central arteriole, in proximity to the red pulp. It contains antigen-presenting cells (APCs), such as dendritic cells and macrophages. Some of the white pulp's macrophages are of a specialized kind known as metallophilic macrophages.^[2]