What scientific break through helped the Endocrine or the Lymphatic system?

One significant scientific breakthrough that aided the understanding of the endocrine system was the discovery of hormones and their functions in the early 20th century, particularly the identification of insulin in 1921, which transformed Diabetes treatment. In the lymphatic system, the discovery of lymphatic vessels and their role in immune response, advanced by research into the lymphatic system's anatomy and function, has enhanced our understanding of diseases such as cancer and lymphedema. These breakthroughs have led to targeted therapies and improved patient outcomes in related conditions.