Why does the actions of the thymus demonstrate a close functional connection between the lymphatic system and the endocrine system?

The Thymus is a unique gland which protects the body against autoimmunity when the immune system act against itself. Hence the Thymus plays a significant role the dual systems i. e., the lymphatic system (body's defensive mechanism) and the endocrine system

Explanation:

The Thymus is special gland located anteriorly to the chest directly behind the sternum and in between the lungs. Active until puberty and gradually shrinks to become fat after puberty.

Function: Prior to birth and during childhood thymus engage in producing and maturation of T-lymphocytes or T-cells a particular type of white blood cells which defence the body against infectious disease germs. Though the organ does not function throughout the life span but it plays a significant role protecting the body against autoimmunity refers to an immune system works against itself. Therefore the thymus plays a key role in lymphatic system and an endocrine system.

Secretion:Thymus secretes Thymosin a hormone it instigates the development of T-Cells (disease resisting cells) Thymosin stimulates the development of T-Cells until a human attains its puberty. At the age of 75 thymus becomes a fatty tissue.