8- Lymph node VM

Question 1

Where are lymphocytes generated and become mature?

Answer 1

In the primary lymphatic organs (BM and thymus)

Question 2

Where do lymphocytes mount an immune response?

Answer 2

Secondary lymphatic organce (lymph nodes)

Question 3

What is the “mesh” support system of secondary lymphatic organisms? What is it composed of?

Answer 3

Stroma (made of reticular fibers)

Question 4

What are the main cells of the lymph node parenchyma and where are they located?

Answer 4

• B cells (peripherally in follicles within the cortex)
• T cells and macrophages (in the paracortex and medulla)

Question 5

Contrast the appearance of primary and secondary lymphoid follicles; why are they different?

Answer 5

• primary= uniform dark staining (consist mostly of naive B cells)
• secondary= lighly staining germinal ceneter surrounded by darker staining mantle zone (indicates B cells have been activated by the presence of a foreign antigen in the lymph fluid)

Question 6

What is the functional significance of a germinal center in a lymph follicle?

Answer 6

A germinal center indicates that new B cells are being produced in response to an antigenic stimulus

Question 7

What is the functional significance of high endothelial venules in the lymph node?

Answer 7

HEVs are the “conduit” by which lymphocytes enter and are sequestered within lymph nodes

Question 8

When you palpate a patient’s cervical “swollen glands”, what are you really palpating? What is happening at the cellular level in these structures?

Answer 8

• Palpating lymph nodes that are enlarged and have triggered a pain response
• Nodes are enlarged due to reactive changes in the lymph node including:
  
  • follicular hyperplasia (B cell proliferation forming germinal centers)
  • paracortical hyperplasia (T cell proliferation)
  • sinus histiocytosis (expanded sinuses)