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primary vs secondary lymph tissue?
primary: where lymphocytes proliferate in a protected environment - thymus and bone marrow
secondary: where immunocompetent lymphocytes proliferate in response to exposure to antigen -- spleen and lymph nodes -- filtering blood and lymph respectively
- germinal center: starry sky appearance, created by macrophages
- mantle: oriented towards lumen, where antigens meet lymphocytes
epithelium of palatine tonsil?
significance in lymphoid tissue?
stratified squamous epithelium, lymphocytes can invade
tonsils: # of crypts, type of epithelium
- palatine - multiple, deep, strat sqaum
- pharangeal - no real ones, respiratory
- lingual - shallow, nonkarat strat squam
layers of lymph node.
- Cortex: contains lymph nodules, B lymphocytes
- Paracortex: T lymphoctes
- Medulla: cords and sinuses, which are continuous with the capsular and cortical sinues
-network of reticular tissue -- reticular cells and elongated nuclei...in sinus spaces
fluid flow in lymph node
- lymph: affterent to convex surface, out of hilum -- through sinuses...capsular, cortical, paracortical, and medullary
- blood: in and out of hilum
high endothelial venules?
- 1. in paracortical lymph node, spleen, tonsils and peyers patches.
- 2. allow lymphocytes to get back from blood into lymph tissue
Blood flow through spleen?
enter and exit through hilum, travel through slpeen through trabeculae/ trabecular arteries, then central arteries surrounded by (PALS) and lymphoid nodules. After sheaths comes the red pulp where the arteries either end in sinusoids or terminates as open ended vessels in red pulp. Red blood cells are checked while travelling from arteries to sinusoids, and then leave by trabeculae and splenic veins.
Lyphoid Tissue in Spleen
Either PWP, peripheral white pulp: B lymphocytes
or PALS, periarterial lymphatic sheaths: T lymphocytes
Red Pulp of Spleen
spongy network of sinusoids lined by discontinuous endothelial cells
Lobules each with a dark cortex and lighter medulla that houses a Hassal's corpuscle.
Lobules divided by septa with blood vessels.
Medullas communicate with each other.
What is a hascle's corpuscle?
concentrically arranged epithelioreticular cells....they also for the framework for the rest of the lobule.
Epithelial reticular cells of the thymus?
- -large pale nuclei surrounded by eosinophilic cytoplasm
- -more easily distinguished in the medulla