Histology of the Thymus

Question 1

What is the flow of lymph to and from a lymph node?

Answer 1

Thanks you for AST(ask) ME this question:

Afferent vessel–> Subcapsular sinus–>Trabecular sinuses–>Medular sinuses–>Efferent vessel

Question 2

Where are B-cells located in the lymph node?

Answer 2

Nodular cortex and medula

Question 3

Where are T-cells located in the lymph node?

Answer 3

Paracortex

Question 4

What is the high endothelial venule?

Answer 4

The site of Diapedesis.

Cells in the HEV are round and protrude to the lumen.

Question 5

How is the vascular system in the thymus different from the Lymph node?

Answer 5

Thymus endothelial cells have tight junctions in the blood-thymus barrier.

This protects the thymocytes (baby t cells)

Question 6

T/F: There is an afferent lymphatic vessel in the thymus.

Answer 6

False

There is NO afferent lymphatic to the thymus!

Question 7

Look up histological differences between Lymph node, thymic tissue, and spleen.

Find slides online

Answer 7

https://web.duke.edu/histology/NormalBody/Lymphatic/Lymphatic.html

Question 8

How do you identify a Hassalls corpuscle on a histology slide of the thymus? What does the HC do?

Answer 8

They are big red blobs.

Is a potent source of TSLP which helps mature dendritic cells.

Question 9

How do you identify a epithelal reticular cells on a histology slide of the thymus?

Answer 9

They usually have a large “white space” around them compared to the other cells in the area.

Question 10

T/F: There is no afferent lymphatic vessel in the spleen

Answer 10

TRUE.

Much like the Thymus there is no afferent lymphatic vessel

Question 11

What do you find in the red pulp of the spleen? What is its function?

Answer 11

RBC
Platelets 
Granulocytess
Macrophages
Plasma

Fxn: filter blood, antigens, old RBC.

Question 12

What do you find in the white pulp of the spleen? What is its function?

Answer 12

B and T cells
Macrophages

FXN: Mount immune responses to antigens.

Question 13

Give examples of some MALT tissues.

Answer 13

MALT= mucosal-associated lymphoid tissue

• Tonsil
• Esophageal and bronchial nodes
• Appendix
• Peyer’s Patch

Question 14

What kind of immune cells are in respiratory and GI MALTS?

Answer 14

M-cells

Question 15

What are the fxns of the lympatic system?

Answer 15

• Removal of interstitial fluid from tissues
• Absorb and transport fatty acids
• Transport WBC to and from lymph nodes
• Lymph transports APCs to lymph nodes
• 2 cells and a Fat Fluid

Question 16

What do helper T cells express, recognize, and do?

Answer 16

Express CD3 and CD4
Recognize MHC class II
Help recruit other cells

Question 17

What do cytotoxic T cells express, recognize, and do?

Answer 17

Express CD3 and CD8
Recognize MHC Class I
Destroy pathogens

Question 18

What do b-cells express, recognize, and do?

Answer 18

Express CD20
Recognize antigens
Secrete antibodies

Question 19

What the difference between a primary and secondary lymph organ?

Answer 19

Primary (Bone Marrow and Thymus)- Maturation occurs here. Primary site of B and T cells.

Secondary does not have maturation.

Question 20

Which type of lymphatic tissue does not have any type of capsule?

Answer 20

Lymph nodules (ex peyers patch)

Tonsils are covered by stratified squamous on one side.

Question 21

Which type of lymphatic tissue(s) has NO germinal centers?

Answer 21

• Lymph nodules Primary

- Thymus

Question 22

Which type of lymphatic tissue(s) has a lobulation?

Answer 22

Thymus

Question 23

What is the function of a lymph node?

Answer 23

Filter non specific debris.

Site for antigen presentation to B-cells.

Question 24

What are important structural features of the thymus?

Answer 24

-Bi lobed
-Medula: dense thymocyte
-Cortex: less dense t-cyte
Blood-thymus barrier (stromal cells)

Question 25

What are some important functions of the thymus?

Answer 25

+/- selection of thymocytes

Hassal’s corpuscles secrete TSLP which directs maturation of DCs.

Question 26

What are important structural features and fxns of the Spleen?

Answer 26

Red and White pulp

FXN: Adaptive immunity.
Recycle blood via macrophages.
Store Platelets

Question 27

What are important structural features and fxns of MALTs?

Answer 27

• No capsule
• Lymphocyte accumulation

FXN: Mucosal protection.