Origin
- Develops from the endoderm of the embryo
- It is located in the upper chest region beneath the breastbone in front of the heart
- It is a soft, roughly triangular, bilobed mass of lymphoid tissue.
- The shape resembles that of a thyme leaf.
- The external surface of the thymus is covered by a connective tissue called the capsule.
- Each lobe of the thymus is divided into several lobules. The outer zone of the lobe is called the cortex and the inner zone is called the medulla.
- The thymus is mainly made of two types of cells; the lymphocytes and the reticular cells