There are three locations of the leucocytes in the organism: red bone marrow (30%), peripheral blood (20%) and peripheral tissues (50%).
Red bone marrow. There are 4 pools of leucocytes:
pool of stem cells, which are in rest state. It is insignificant and it is the reserve for blood formation;
mitotic pool. These cells are in division state;
maturating pool. These cells are differentiating; their maturating period is 3-5 days;
reserve pool. These are mature leucocytes, which can enter the bloodstream.
Peripheral blood. There are 2 pools of leucocytes:
pool of circulating leucocytes (50%);
parietal (marginal) pool (50%).
Peripheral tissues have:
migrating leucocytes;
leucocytes in rest state.