Exam III - Lymphatic System

Question 1

What are the primary lymphatic organs?

Answer 1

1. bone marrow
2. cloacal bursa/bursa of fabricus (birds only)
3. thymus

Question 2

What are the secondary lymphatic organs?

Answer 2

1. lymph nodes
2. spleen
3. mucosal associated lymphoid tissue

Question 3

What is the function of the lymphatic system?

Answer 3

to protect the body against pathogenic organisms and their products and to help in the removal and disposal of cells undergoing natural and induced degenerations

Question 4

Where do B cells mature?

Answer 4

bone marrow

Question 5

Identify the arrows marked ‘A’ in this H&E section of the canine thymus

Answer 5

septae

Question 6

Identify the arrows marked ‘B’ in this H&E section of the canine thymus

Answer 6

cortex

Question 7

Identify the arrows marked ‘C’ in this H&E section of the canine thymus

Answer 7

medulla

Question 8

In the thymic cortex, __________ phagocytose and eliminate dead T cells. They are frequent near the medulla.

Answer 8

Tingible body macrophages (also called starry sky macrophages)

Question 9

large, central calcified or degenerated cells surrounded by concentric circles of keratinized cells in the thymic medulla:

Answer 9

thymic corpuscles, or Hassal’s corpuscles

Question 10

The left half of this H&E section of canine thymus would be referred to as the ________. The right half would be the __________.

Identify the labeled structures.

Answer 10

The left half of this H&E section of canine thymus would be referred to as the cortex (with tightly packed small lymphocytes). The right half would be the medulla (less compact).

A - macrophage (can tell due to the space surrounding it)

B - Hassal’s corpuscles

Question 11

What is the function of lymph nodes?

Answer 11

to filter antigens from lymph before returning it to the bloodstream

Question 12

What are the arrows pointing to in this H&E section of a canine thymus?

Answer 12

Hassal’s corpuscles (or thymic corpuscles)

Remember, these corpuscles are characteristic of the thymus!

Question 13

____________ are where lymphocytes can leave the blood stream and enter into the lymph nodes

Answer 13

High endothelial venules

Question 14

Identify the area labeled ‘A’ in this H&E section of a lymph node.

Answer 14

Cortex

Question 15

Identify the area labeled ‘B’ in this H&E section of a lymph node.

Answer 15

medulla

Question 16

Identify the structure labeled ‘C’ in this H&E section of a lymph node.

Which type of cell will be found here primarily?

Answer 16

Follicle; B-cells

Question 17

In this H&E section of a tonsil, is this a primary or a secondary lymphoid follicle? How can you tell?

Also, label A and B, biatch!

Answer 17

This is a secondary follicle. You can tell because of the very defined marginal zone surrounding the germinal center.

A - marginal zone

B - germinal center

When stimulated by antigen, they will change histologic morphology from primary lymphoid follicles to secondary lymphoid follicles

Question 18

Identify A and B in this H&E section of a subscapular sinus

Answer 18

A - macrophages

B - reticular cells

Question 19

What type of cell do you find in the paracortex primarily?

Answer 19

T-cells

Question 20

Identify the arrows in this H&E section of a lymph node.

Answer 20

high-endothelial venules (diapedesis)

Question 21

Identify the regions labeled ‘A’ and ‘B’ in this H&E section of the medulla.

Answer 21

A - cords (dense area where cells appear to be migrating)

B - sinus

Question 22

Identify the type of cell indicated by the arrow in this H&E section of a medulla sinus.

Answer 22

plasma cell (you can tell based on the very prominent cytoplasm)

Question 23

_________ occurs when the thoracic duct is ruptured.

Answer 23

chylothorax

Question 24

Most lymphocytes migrating to lymph nodes enter from the _____________.

Answer 24

Most lymphocytes migrating to lymph nodes enter from the peripheral blood.

Question 25

Identify the areas labeled A and B in this H&E section of a spleen

Answer 25

A - white pulp (primarily lymphoid tissue)

B - red pulp (sinusoids)

Question 26

In which of these regions will immune response occur?

(H&E section of a canine spleen)

Answer 26

White pulp - lymphocytes

Question 27

what is immediately surrounding the central arteriole in this H&E section of a lymphoid follicle?

Answer 27

periarteriolar lymphoid sheath (T-cells)

(peri = next to) + (arteriolar) = next to the arteriole

Question 28

____________ is the greatest collection of lymphocytes in the body

Answer 28

**Gut-Associated Lymphatic Tissue (GALT) **is the greatest collection of lymphocytes in the body

Includes:

• Solitary and aggregated lymphatic nodules
• Intraepithelial lymphocytes
• Subepithelial lymphocytes
• Plasma cells
• Macrophages

Question 29

Identify the structure labeled ‘2’ in this H&E section of a feline pyloric stomach.

Answer 29

diffuse lymphatic tissue

Question 30

Identify the area labeled ‘7’ in this H&E section of a feline pyloric stomach.

Answer 30

mucosa

Question 31

Identify the structure labeled ‘4’ in this H&E section of a feline pyloric stomach.

Answer 31

lymphatic nodule

Question 32

Identify the area labeled ‘3’ in this H&E section of a feline pyloric stomach.

Answer 32

germinal center

Question 33

Identify the area labeled ‘10’ in this H&E section of a feline pyloric stomach.

Answer 33

submucosa

Question 34

Identify the area labeled ‘8’ in this H&E section of a feline pyloric stomach.

Answer 34

muscularis externa

Question 35

Identify A and B in this H&E section of the small intestine

Answer 35

A - lacteals

B - lymphoid follicles (Peyer’s patches)

Question 36

Identify the structures labeled 1, 2, and 3.

Answer 36

1 - small lymphatic vessel with a valve: clear content, no erythrocytes, occasional lymphocytes

2 - Arteriole; 1-3 layers of circular smooth muscle walls

3 - venule; no smooth muscle in the wall