Histology of Immune Organs

Question 1

Where the peripheral (secondary) lymphoid sites?

Answer 1

• MALT (mucosa-associated lymphoid tissues) of the respiratory, gastrointestinal, and urogenital tracts
• Lymph nodes
• White pulp of spleen

Question 2

What’s found in the center of lymphoid follicle?

Answer 2

-This is called the germinating center.
-Fibroblastic reticular cells (aka mesenchymal reticular cells) which secrete Type 3 collagen.
-Centroblasts: B cells undergoing differentiation.
Dendritic cells (also located in mantle)
-Lots of B cells
-APCs like macrophages
-Cells undergoing differentiation (mitotic figures).
-Cells undergoing apoptosis

Question 3

What is found in outer region of lymphoid follicle?

Answer 3

-Mostly T cells

Question 4

What’s in lymph node?

Answer 4

• Lymphoid follicles located near the cortex.
• Trebeculae (made of Type I collagen) running from cortex inwards which help shape the
• sinuses

Question 5

What type of immunoglobin is found mainly in spleen?

Answer 5

IgG

Question 6

What does hemoglobin break down into

Answer 6

• Globin and Heme
• Globin is broken down into amino acids
• Heme becomes bilirubin and iron+transferrin
• bilirbin is sent to liver b/c toxic
• iron+transferrin sent to bone marrow