Thymus

• Thymus is a BILOBED organ located in the MEDIASTINUM between the STERNUM and the AORTA.
• Thymus has a REDDISH appearance in the living body due to a RICH BLOOD SUPPLY.
• After puberty, the ADIPOSE and AREOLAR connective tissue begin to replace the THYMIC TISSUE which is YELLOW in color.
• By the time a person reaches maturity, the functional portion of the gland is REDUCED considerably, and in old age the functional portion may weigh only 3 g.
• Before the thymus atrophies, it populates the SECONDARY lymphatic organs and tissues with T CELLS.
• Each thymic lobule consists of a deeply staining OUTER CORTEX and a lighter-staining CENTRAL MEDULLA.
• Cortex: IMMATURE T-CELLS from the RED BONE MARROW migrate to the THYMUS where they MATURE.
• Medulla: More MATURE CELLS, epithelial cells, dendritic cells, and macrophages.