White blood cells are primarily made in the bone marrow, which is the soft, spongy tissue inside many bones such as the vertebrae, hip, leg bones, ribs, shoulder, and collarbone
. Specifically:
- All white blood cells originate from hematopoietic stem cells in the bone marrow
- Most white blood cells develop and mature in the bone marrow before entering the bloodstream
- Two types of white blood cells, lymphocytes (T cells and B cells), mature in lymphatic organs: T cells mature in the thymus gland, while B cells mature in the lymph nodes and spleen
Thus, the bone marrow is the central site for the production of white blood cells, with some lymphocytes maturing further in lymphatic tissues.
