The effect of single and double trauma on the mitotic activity of bone marrow and thymus.

Different types of trauma and antigenic challenge bring about significant increases in the mitotic rates of bone marrow and thymus. This cell response probably occurs in order to produce leucocytes and macrophages, which are needed for the defence of the organism on injury. The present investigation shows that when two traumatic injuries take place only two days after each other, the cell response to the second trauma becomes completely abolished. With an interval of 10 days, however, the cellular proliferation has returned although delayed.