LYMPH NODE
- Lymph nodes are secondary lymphatic organs.
- Small kidney-shaped organs.
- Size from 1-25 mm.
- The total number in the body ~500 Distributed throughout the body along the network of lymphatic vessels.
- Function: filters the lymph, stores lymphocytes (T & B and other WBCs).
- They are common in the:
- 1. Armpits → Called the axillary lymph nodes.
- 2. Groins → ″ ″ inguinal, ″ ″
- 3. Neck → ″ ″ cervical ″ ″.
- 4. Knees → ″ ″ popliteal ″ ″.
Structure:
- 1. Capsule :
- Outer layer
- Dense connective tissue
- Providing structural support and protection.
- 2. Subcapsular Sinus:
- Space beneath the capsule
- Recieve afferent lymphatic vessels (ducts).
- Contains macrophages help filter and capture debris and foreign particles in the lymph.
- 3. Trabeculae: fibrous extensions from the capsule that divide the lymph node into compartments.
- Contains Blood vessels & lymphatic vessels.
- 4. Cortex:
- Outer cortex 1°↗2°
- Contains follicles of B cells
- have Germinal Center.
areas where B-cells differentiate into plasma cells.
- Inner cortex: No follicles (Paracortex) ↘ T-cells area.
- 6. Medulla:
- Innermost part.
- Medullary cords: Extends from the cortex to the medulla, containing B cells, T cells & plasma cells.
- Medullary Sinuses: Spaces contain lymph.
- 7. Hilum: Area where blood vessels and efferent lymphatic vessels.