Where do white blood cells form?

Answer 1

White blood cells or leukocytes are formed in the bone marrow (within the bones).

Amongst other things, they are primarily responsible for controlling infections in the body.

When the bodies white blood cell counts drop for some reason (cancer, chemotherapy etc), the ability to fight infection is compromised.

Answer 2

White blood cells, or leukocytes (also spelled "leucocytes"; from the Greek word leuko- meaning "white"), are cells of the immune system involved in defending the body against both infectious disease and foreign materials. Five[1] different and diverse types of leukocytes exist, but they are all produced and derived from a multipotent cell in the bone marrow known as ahematopoietic stem cell. They live inbetween 6 hours and two days. Leukocytes are found throughout the body, including the blood and lymphatic system.[2]

The number of leukocytes in the blood is often an indicator of disease. There are normally between 4×109 and 1.1×1010 white blood cells in a litre of blood, and ranging from 7 and 21 micrometres in diameter, they make up approximately 1% of blood in a healthy adult.[3] An increase in the number of leukocytes over the upper limitsis called leukocytosis, and a decrease below the lower limit is called leukopenia. The physical properties of leukocytes, such as volume, conductivity, and granularity, may change due to activation, the presence of immature cells, or the presence of malignant leukocytes in leukemia.

Answer 3

Bone marrows (stem cells) and lymph nodes.

Answer 4

Red bone marrow

Answer 5

Yellow Bone Marrow