The bone marrow and stem cells

The full name for stem cells in the blood and bone marrow is haemopoietic stem cells, but in this section we shorten it to stem cells.

Bone marrow is a spongy material found inside the bones - particularly the bones of the pelvis. The bone marrow is where stem cells are made. Stem cells are blood cells at their earliest stage of development. All blood cells develop from stem cells.

The three main types of blood cells are:

• red blood cells, which carry oxygen to all cells in the body
• white blood cells, which are essential for fighting infection
• platelets, which help the blood to clot and prevent bleeding.

When the cells are fully mature, they’re released into the bloodstream. 

Stem cells are mainly found in the bone marrow. There are usually only a very small number in the blood. Doctors can stimulate a person’s stem cells to move from their bone marrow into their blood. They can do this by giving them injections of proteins known as growth factors|. This is sometimes called mobilising stem cells. 

Stem cells can then be collected from the blood. Sometimes stem cells are collected directly from the bone marrow. 

Bone and bone marrow
View a large version of the image of the bone and bone marrow|