This is tangentially related. Ever wonder how B-cells (antibody producing white blood cells) got their name?

They are named after the Bursa of Fabricius, a lymphatic organ in birds that serves as the site of B-cell maturation. (Their sister cells, T-cells, mature in the thymus). Stem cells migrate from the liver to the Bursa of Fabricius, where they differentiate and mature into B-cells.

B-cells were first discovered in the Bursa fabricii of birds, that’s why they are named B-cells. The bursa equivalent in humans is the bone marrow.