| 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 | |
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]