Term
first degree (central) lymphoid organs
Second degree (peripheral) lymphoid organs
Thrird degree
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Definition
1) central: thymus, bone marrow
2) peripheral: lymphnodes, spleen, tonsils, peyers patches, appendix
3) third degree: pathological like a pannus in an arthritic joint
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Term
| Two key parts of lymphoid organ |
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Definition
1) stroma: scaffolding, reticular fibers except thymus (sits to hold organ together)
2) parenchyma: lymphocytes, macrophages, dendritic cells, natural killer cells (spleen) |
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Term
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Definition
| - ventral part of third pharyngeal pouch and third branchial cleft. Endoderm and underlying mesoderm origin. |
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Term
| What is the capsule of the thymus and what makes it up? |
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Definition
| - capsule is formed fibroblasts that for form trabeculae or septa which separate the cortex into lobules |
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Term
| Three components of the stroma of the thymus and their cell types |
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Definition
1) Cortex: developing T cells (CD3-4-8-), Nurse cells that secrete IL 7, cortical epithelial cells
2) Cortico medullary junction: dendritic cells which contact with CD3+4+8+ , macrophages also make contact and ingest apoptotic cells
3) Medulla: Mature T-Cells (CD3+4+ or CD3+8+) |
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Term
Where are hassall's corpuscle's found?
What happens to them with age?
What is their function? |
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Definition
| Medulla of thymus, no known function, increase with age |
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Term
| Parenchyma: where the developing T-cells go |
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Definition
Subcapsular: 5% of all thymocytes which are mainly large blasts; CD 3-4-8- cells proliferate for a week
Mid cortex to cortico-medullary junction: CD3+4+8+ mature for 2 weeks.
positiveselection then negative selection |
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Term
| basis for positive/negative selection of T-cells in cortico-medullary junction of thymus |
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Definition
| - must be able to interact with MHC but not too well (self vs. self recognition) |
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Term
| Where do natural killer cells come from? |
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Definition
Emerge from bone marrow and divergy early from the Pro T/NK pathway
NOT thymus dependent |
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Term
| Growth factors for thymocyte development |
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Definition
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Term
| Where are blood vessels and efferent lymphatics found in lymph nodes? |
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Definition
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Term
What creates the lymph sinuses?
Three types of lymph sinuses
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Definition
- reticular stroma makes up lymph sinuses
- sucapsular, trebecular and medullary
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Term
| Lymphatic circulation in lymphnode |
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Definition
| afferent lymphatics -> subcapsular -> trebecular -> medulary sinuses -> efferent lymphatic -> thoracic duct |
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Term
| Three key types of cells in the sinuses of lymphnodes |
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Definition
1) B lymphocytes
2) T lymphocytes
3) Macrophages |
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Term
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Definition
| - Hilar artery -> cortical nodule cpaillaries -> deep cortical post -> capillary venules -> Hilar vein |
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Term
Two nodules in cortex of lymphnode
Two things that B cells can mature into |
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Definition
1) first degree nodule: B cells mainly
2) second degree nodule: sites where B cells mature with help of CD4+ T Cells into:
a) Plasmablasts
b) Memory cells |
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Term
| Germinal Center Zonation: zones and what happens in them |
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Definition
1) Follicular mantle: storage of long-lived memory B-cells
2) Apical light zone: differentiation of selected centrocytes
3) Basal light zone: Apoptotic death
4) Dark zone: Proliferation of centroblasts |
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Term
| Centroblasts: what are they and where do they exist? |
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Definition
- B-blasts w/o surface immunoglobin
- dark zone of germinal center in lymphnode |
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Term
| Centrocytes: what are they and where do they exist |
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Definition
- B cells with surface immunoglobin
- exist in basal light zone of germinal center of lymph node (and apical light zone) |
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Term
| What does the paracortex of a lymph node contain? |
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Definition
- T-cells and some B
- langerhan cell
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Term
High endothelial post capillary venule: what do they do
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Definition
| function as the gate of entry of t and b cells form the circulation into the lymphnode |
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Term
| Where do long lived plasma blasts go? |
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Definition
| - leave medullary cords and go into circulation to the bone marrow via efferent lymphatics |
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Term
Spleen red pulp
Type of capillaries |
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Definition
- RP cords which can extend from the white pulp
- sinusoids with macrophages attached and penicillar artereis come from central arteries and may empty into sinusoids or RP cords |
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Term
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Definition
| Periarteriolar lymphoid sheath: 1oT cells ensheathing artery |
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Term
Function of marginal zone
What it contains (three cell types) |
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Definition
- separates white and red pulp
- memory B cells, T independent B cells, macrophages |
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Term
| What does open vs. close circulation refer to in spleen with regards to pencillar arteries? |
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Definition
open: pencillar arteries go to parenchyma of RP cords and then into sinusoids
Closed: pencillar arteries go directly into sinusoids |
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Term
| How destruction of RBC's takes place in spleen? |
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Definition
| - RBC's loose surface sialic acid exposing surface galactose which are phagocytosed by sinusoid macrophages |
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Term
| Circulation in spleen (order of arteries) |
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Definition
Trabecular artery -> central arter (ensheathedin 1oT cells) -> pencillar arteriole -> sinusoid
or pencillar arteriole -> RP cord -> sinusoid |
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Term
What types of lymphoid cell are present in epithelial lining of GI tract?
What do they do? |
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Definition
CD3+8+ alpha-beta
and CD3+ yg
- monitor luminal antigens
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Term
| Two nodules and what they contain in GI tract |
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Definition
first degree nodule: B cells that produce IGA
Second degree nodule: B cells and some T cells (germinal center) |
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Term
| Two common structures in Peyer's patches |
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Definition
1) Villi
2) Domes
(these overlay lymphoid tissue) |
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Term
| What type of cells overlay domes of peyer's patches? |
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Definition
| - M cells which are antigen transporting epithelial cells |
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Term
| similarities between spleen and lymphoid tissue of GI tract? |
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Definition
- periarteriolar lymphoid sheaths are present as well as all along the GI tract
- high endothelial venules in internodular tissue also present as means for B and T cells to enter the pery's patches |
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Term
| Different between appendix and rest of GI lymphoid tissue |
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Definition
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Term
Types of cells lining:
Palatine tonsil
Pharyngeal
Lingual |
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Definition
Palatine: startified squamous
Pharyngeal: pseudostratified ciliated columnar and stratified squaous
Lingueal: stratified squamous |
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Term
| presence of crypts in palatine, lingual and pharyngeal |
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Definition
palatine: many deep crypts
pharyngeal: no crypts but shallow pleats
lingual: single crypt |
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Term
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Definition
| - found under all epithelial linings of the mucosa (respiratory, gut, urinary) |
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Term
| circulation of lymphocytes |
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Definition
- lymphocytes leave the blood thru HEV in lymph nodes and peyers patches.
- eventually enter efferent lymphatics and the thoracic duct system
- TD joins left subclavian and inter jugular veins |
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