The thymus is different from other lymphoid organs both in terms of its structure and in its function
Structurally, the thymus consists of supporting cells and lymphocytes
However, unlike in other lymphoid organs, the supporting cells are epithelial cells which form a three dimensional framework in which the lymphocytes are supported
The thymus is divided into lobes and lobules by thin connective tissue septae
Each lobule has a cortex and a medulla
In the cortex there is a high density of small lymphocytes
These lymphocytes proliferate
In the medullary regions, the density of small lymphocytes is less than in the cortex
Functionally, the thymus is a site of the production of T lymphocytes
It is not a site at which foreign antigens are monitored
The T lymphocytes produced in the thymus are distributed in the blood to other lymphoid organs such as the spleen and lymph nodes, and to areas of non-encapsulated lymphoid tissue
In these areas, the T lymphocytes produced in the thymus will participate in immune functions