High Endothelial Venules (HEV; #1 and #2) - venules with unusually tall endothelial cells through which lymphocytes in the blood enter the node. HEVs are found in the inner cortex.
Medulla - inner part of the node. The cells are arranged in medullary cords surrounded by medullary sinuses.
Lymph Node (Silver)
Click the thumbnail to show this specimen stained with silver.
Lymph nodes is one of the tissues that has a framework (or stroma) of reticular fibers.
Reticular fibers are composed of thin and delicately woven strands of type III collagen. They are not visible with hematoxylin & eosin (H&E) or azan, but are specifically stained by silver. This renders them black and makes them easily distinguishable from type I collagen fibers that are stained red/brown.
Capsule - contains a mixture of collagen fibers (red) and reticular fibers (black).
Trabeculae - contain a mixture of collagen fibers (red) and reticular fibers (black).
Cortex - reticular fibers form an irregular, anastomosing network in the outer region of the node. Nodules are enclosed by reticular fibers.
High Endothelial Venules (HEV; longitudinal and cross-section) - venules with unusually tall endothelial cells through which lymphocytes in the blood enter the node.
Medulla - reticular fibers form networks to support the medullary cords throughout the inner part of node.