Red and white pulp
Cut across, the spleen is mostly red pulp, a sponge of blood-filled spaces where worn-out red cells are caught and broken down. Scattered through it are grey-white dots about a millimetre across, the white pulp. Each is a sheath of lymphocytes round a small artery, with T cells next to the artery and B cells in round follicles beside it.
A spleen cut across, its injected veins branching through the spongy pulp, Gray's Anatomy, 1918, figure 1189Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray1189.png)
The model's cut crosses the upper abdomen at the level of the spleen, seen from above. The stomach lies in front of the spleen and the left kidney toward the spine. The liver fills the right side, and the aorta runs in front of the spine. The pulp is too fine for the model and shows only in the figure.
Blood that enters the spleen passes the white pulp first, so a germ carried in the blood meets the lymphocytes there, and the B cells answer by making antibodies against it.
Sources
- Susan Standring (ed.), Gray's Anatomy, 42nd ed. (2020), ch. 4 and chapter on the spleen.
- Henry Gray, Anatomy of the Human Body, 20th ed. (1918), section XI, The Spleen.
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