Well, earlier we mentioned that the thymus is involved in building up our immune system. So how exactly does this take place and what do we mean by this? Well, inside the bone marrow of our bones, we have white blood cells. And these white blood cells eventually differentiate into different types of specialized cells that are used by our immune system for different purposes. And one of these cells is the T cell, also known as the T lymphocyte, where the T actually stands for thymus. So inside the bone marrow, we produce cells called arithmicides.