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5 Cards in this Set
- Front
- Back
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icreases at slow ratee until puberty
at puberty, begins to involute |
thymus
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structure
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lobes
lobules parenchyma-cortex and medulla stroma-epithelial reticular cells, no CT, secretes thymosin (differentiates T cells), non-phagocytic hassall's corpuscles |
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circulation
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internal thoracic and inferior thyroid aa pass to corticomedullary junction
gives off capillaries to cortex and medulla terminate in medullary venules |
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capillary endothelium connected by occluding (tight) junctions-impermeable to macromolecules
macrophages located in perivascular space outside basal lamina of endothelium (phagocytose Ag molecules that escape capillaries) 3rd layer consists of epithelioreticular cells connected by tight jxns |
blood-thymic barrier
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purpose of blood-thymic barrier
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prevent small lymphocytes in cortex from being sensitized by Ags that escape from cortical capillaries
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