Lymph node
Lymph nodes are kidney or oval shaped and range in size from 0.1 to 2.5 cm long. Each lymph node is surrounded by a fibrous capsule, which extends inside a lymph node to form trabeculae. The substance of a lymph node is divided into the outer "cortex" and the inner "medulla". These are rich with cells. The hilum is an indent on the concave surface of the lymph node where lymphatic vessels leave and blood vessels enter and leave.