Anthony Paganini - Michigan State University
Anthony Paganini - Michigan State University
Anthony Paganini - Michigan State University
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COPYRIGHT NOTICE<br />
According to <strong>Michigan</strong> <strong>State</strong> <strong>University</strong> guidelines, the images contained in this PowerPoint file:<br />
1) are solely for the personal learning of currently registered <strong>Michigan</strong> <strong>State</strong> <strong>University</strong> students duly enrolled in PSL 536,<br />
Medical Cell Biology and Physiology<br />
2) are protected by U.S. copyright laws through their respective publishers indicated below.<br />
3) in part or in whole, may not be reproduced in any form or by any means, including photocopying, except for individual<br />
personal reference.<br />
4) may not be utilized by any information storage and retrieval system, incorporated into a scribe service or otherwise<br />
made public.<br />
Thank you for your cooperation.<br />
PSL 536 Faculty<br />
Colleges of Osteopathic Medicine and Human Medicine<br />
unless otherwise noted, figures, tables or schematics are taken from:<br />
AB: Abbas & Lichtman, Basic Immunology, 3/e, 2009, Elsevier<br />
L: Langman's Medical Embryology, 11/e, 2010, Lippincott, Williams & Wilkins<br />
M: Moore & Dalley, Clinically Oriented Anatomy, 6/e, 2010: Lippincott, Williams & Wilkins<br />
MT: Martini & Timmon, Human Anatomy 5/e, 2006, Pearson<br />
G: Gilroy, Atlas of Anatomy, 1/e, 2008, Theime<br />
N: Netter, Atlas of Human Anatomy 5/e, 2011: Elsevier<br />
R: Ross, Histology, 5/e, 2006: Lippincott, Williams & Wilkins<br />
RB: Rhoades & Bell, Medical Physiology, 3/e, 2009: Lippincott, Williams & Wilkins<br />
1
Brief Introduction<br />
The organs and tissues of the lymphatic system make it possible for the body to monitor and protect itself<br />
from xenogenic (foreign, non-self) invaders and other antigenic challenges regardless of route of entry. The<br />
THYMUS produces mature, immunocompetent, yet naive, T lymphocytes and destroys a subset of these T<br />
lymphocytes which would otherwise maladaptively react to self antigens. LYMPH NODES monitor and filter<br />
lymph fluid for foreign invaders, the SPLEEN monitors and filters blood, and the MUCOSAL ASSOCIATED<br />
lymphatic TISSUE (MALT) guards against pathogens which attempt to cross the mucosal boundaries of the<br />
digestive, respiratory, or urogenital tracts. These geographically and histologically diverse tissues and organs<br />
actually have several structural features in common that promote monitoring and interactions among<br />
immune system cells and foreign invaders.<br />
Most lymphatic system organs or tissues have a reticular 'chicken-wire' ultrastructure to promote easy<br />
movement of body fluids, cells, antigens, and hence intercellular interactions. The lymph nodes, spleen, and<br />
MALT contain specific tissues regions in which B and T lymphocytes congregate. As you will learn in<br />
immunology, this is ultimately related to adaptive and innate immune system responses.<br />
Lymphocytes recirculate throughout the lymphatic tissues and organ and the method of recirculation in lymph<br />
nodes and MALT requires specialized blood vessels called high endothelial vessels (HEVs). HEVs regulate the<br />
egress of lymphocytes from the blood vascular network into the parenchyma of these lymphatic structures.<br />
The bulk movement of lymphocytes in lymphatic tissues is an important aspect of immune system function<br />
and will be discussed for each lymphatic structure.<br />
NOTE: The taxonomy, cell biology, and intercellular communication of the numerous immune system cells<br />
will be detailed in your immunology course this semester.<br />
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The major stroma proteins are reticular protein fibers (Type III collagen) form a supporting fine<br />
mesh-like scaffolding throughout the lymph node. Reticular cells synthesize reticular protein fiber<br />
and ground substance and are indistinguishable from typical fibroblasts<br />
Other cell types of stroma<br />
dendritic cells<br />
derived from red bone marrow and are the primary, 'professional', antigen presenting cells in<br />
lymph nodes<br />
process and present antigens to certain T lymphocytes and are usually found in T cell dense<br />
areas of the lymph node<br />
follicular dendritic cells<br />
have a similar antigen presenting cell (APC) function analogous to dendritic cells but come<br />
from a different cell lineage.<br />
FDCs reside specifically in lymphatic follicles (a.k.a. lymphatic nodules) of lymph nodes and<br />
are the APCs for the B lymphocytes in the lymphatic follicles<br />
macrophages<br />
phagocytize dysfunctional cells and cell debris after an immune battle; are also APC for T-cells<br />
3
Lymph Node Parenchyma- Cortex<br />
outer region of lymph node consisting of a dense collection of lymphocytes (including plasma cells<br />
derived from B lymphocytes), macrophages, dendritic cells, reticular cells, and reticular fibers<br />
afferent lymphatic vessels bring lymph (hence potential antigenic challenges) into the cortex and<br />
this lymph is distributed through an interconnected network of lymphatic vascular spaces called the<br />
cortical sinuses and trabecular sinuses.<br />
Superficial Cortex<br />
a.k.a. Nodular Cortex; loosely referred to as the "B Cell Zone"<br />
location of two types lymphatic follicles (Ross: lymphatic nodules): Primary and Secondary<br />
Primary Lymphatic Follicles of the Lymph Nodes<br />
spherical aggregates of mature-naive B lymphocytes that have yet to encounter antigen<br />
typically there are fewer primary lymphatic follicles than secondary lymphatic follicles in a<br />
given lymph node<br />
terminology note: the word 'nodule' and 'follicle' are used interchangeably.<br />
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