Exam #3: Lymphatic Tissue & Organs Flashcards
What are the 2 zones of a secondary lymphatic nodule?
1) Mantle Zone, which is dark staining & contains small mature lymphocytes
2) Germinal Zone, which is light staining & contains medium to large size & immature lymphocytes
Solitary Lymphatic Nodule
Temporary
Aggregate Lymphatic Nodule
Permanent
Where are aggregates of lymphatic nodules located?
- Lymph nodules (tonsils, spleen, & lymph nodes)
- Peyer’s Patches
- Appendix
- BALT
What are tonsils?
Aggregates of lymphatic nodules that contain B-lymphocytes
Pharyngeal Tonsils
Respiratory/ Pseudostratified Columnar Epithelium with cilia
Palatine Tonsils
Nonkeratinized stratified squamous epithelium
Lingual Tonsils
Nonkeratinized stratified squamous epithelium
Cell types associated with reticular fibers
- Dendritic cells (APC)
- Macrophages (phagocytic)
- Follicular Dendritic Cells (bind antigen/antibody complexes)
Cortex of a lymph node
B-lymphocytes
Deep Cortex of a lymph node
- T-lymphocytes
- HEV
Medulla of a lymph node
Medullary cords
How does the thymus differ from lymph nodes?
- No afferent lymphatic vessels
- No 3D reticular network
- No lymphatic nodules
- No B-lymphocytes
- No sinuses
Type I epitheloreticular cells
- Form a seal around the cortex of the thymus, separating it from the CT capsule & trabeculae
- Contain occludens junctions
Type II epitheloreticular cells
- Form a meshwork in the midcortex
- Contain desmosomes
- Involved in thymic eduction
Type III epithelioreticular cells
- Deep cortex
- Occulens junctions
- Form a seal between the cortex & the medulla
Type IV epithelioreticular cells
- Associated with Type III cells & participate in establishment of the barrier at the corticomedullary junction
Type V epithelioreticular cells
- Form the meshwork of the medulla
Type VI epithelioreticular cells
- Hassall’s Corpuscles
- Contain mature T-lymphocytes
Layers of the blood thymus barrier
1) Endothelium
2) Basal Lamina
3) Macrophages
4) Type I epithelioreticular cells
DiGeorge Syndrome
- Individuals cannot produce T-lymphocytes
- Lack “cell-mediated” immunity
(Also, do not have parathyroid glands & may die from tetany)
PALS
- Periarterial lymphatic sheath (PALS)
- Tunica adventitia of trabecular arteries infiltrated with T-lymphocytes
Splenic Circulation
1) Splenic artery
2) Trabecular artery
3) Central artery w/ PALS (tunica adventitia w/ T-lymphocytes)
4) Penicillar arteries (no PALS)
5) Arterial capillaries
6) Splenic sinuses
7) General circulation
White Pulp
- Stains blue with hematoxylin
- PALS (T-lymphocytes)
- Splenic Nodules (B-lymphocytes)
Red Pulp
- Stains red with eosin
- Splenic Cords- Filter blood
- Splenic Sinuses
