Histology of the Thymus Flashcards
What is the flow of lymph to and from a lymph node?
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Afferent vessel–> Subcapsular sinus–>Trabecular sinuses–>Medular sinuses–>Efferent vessel
Where are B-cells located in the lymph node?
Nodular cortex and medula
Where are T-cells located in the lymph node?
Paracortex
What is the high endothelial venule?
The site of Diapedesis.
Cells in the HEV are round and protrude to the lumen.
How is the vascular system in the thymus different from the Lymph node?
Thymus endothelial cells have tight junctions in the blood-thymus barrier.
This protects the thymocytes (baby t cells)
T/F: There is an afferent lymphatic vessel in the thymus.
False
There is NO afferent lymphatic to the thymus!
Look up histological differences between Lymph node, thymic tissue, and spleen.
Find slides online
https://web.duke.edu/histology/NormalBody/Lymphatic/Lymphatic.html
How do you identify a Hassalls corpuscle on a histology slide of the thymus? What does the HC do?
They are big red blobs.
Is a potent source of TSLP which helps mature dendritic cells.
How do you identify a epithelal reticular cells on a histology slide of the thymus?
They usually have a large “white space” around them compared to the other cells in the area.
T/F: There is no afferent lymphatic vessel in the spleen
TRUE.
Much like the Thymus there is no afferent lymphatic vessel
What do you find in the red pulp of the spleen? What is its function?
RBC Platelets Granulocytess Macrophages Plasma
Fxn: filter blood, antigens, old RBC.
What do you find in the white pulp of the spleen? What is its function?
B and T cells
Macrophages
FXN: Mount immune responses to antigens.
Give examples of some MALT tissues.
MALT= mucosal-associated lymphoid tissue
- Tonsil
- Esophageal and bronchial nodes
- Appendix
- Peyer’s Patch
What kind of immune cells are in respiratory and GI MALTS?
M-cells
What are the fxns of the lympatic system?
- 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
What do helper T cells express, recognize, and do?
Express CD3 and CD4
Recognize MHC class II
Help recruit other cells
What do cytotoxic T cells express, recognize, and do?
Express CD3 and CD8
Recognize MHC Class I
Destroy pathogens
What do b-cells express, recognize, and do?
Express CD20
Recognize antigens
Secrete antibodies
What the difference between a primary and secondary lymph organ?
Primary (Bone Marrow and Thymus)- Maturation occurs here. Primary site of B and T cells.
Secondary does not have maturation.
Which type of lymphatic tissue does not have any type of capsule?
Lymph nodules (ex peyers patch)
Tonsils are covered by stratified squamous on one side.
Which type of lymphatic tissue(s) has NO germinal centers?
- Lymph nodules Primary
- Thymus
Which type of lymphatic tissue(s) has a lobulation?
Thymus
What is the function of a lymph node?
Filter non specific debris.
Site for antigen presentation to B-cells.
What are important structural features of the thymus?
-Bi lobed
-Medula: dense thymocyte
-Cortex: less dense t-cyte
Blood-thymus barrier (stromal cells)
