hey can’t all be superstars!
When we mentally tick oﬀ the names of the
body’s organ systems, the lymphatic (lim-fat
ik) system and the lymphoid organs
and tissues are probably not the ﬁrst to come to mind. Yet if they failed their quiet
background work, our cardiovascular system would stop working and our immune sys-
tem would be hopelessly impaired.
Tis chapter is a bit unusual in that we will explore two functionally diﬀerent but
structurally overlapping systems, the
lymphoid organs and
returns ﬂuids that have leaked from the blood vascular
system back to the blood. It actually consists of three parts:
A meandering network of
, the ﬂuid contained in those vessels
that cleanse the lymph as it passes through them
lymphoid organs and tissues
provide the structural basis of the immune system.
Tese organs and tissues house phagocytic cells and lymphocytes, which play essential
roles in the body’s defense mechanisms and its resistance to disease. Tese structures
include the spleen, thymus, tonsils, and other lymphoid tissues scattered throughout the
body. Te lymph nodes are also part of this system, and like a keystone, they have im-
portant roles to play in both the lymphoid organs and tissues and the lymphatic system.
Let’s begin by looking at the lymphatic system.
The Lymphatic System and
Lymphoid Organs and Tissues
Distribution and Structure of Lymphatic
Vessels (pp. 752–754)
Lymph Transport (p. 754)
Lymphoid Cells and Tissues
Lymphoid Cells (p. 754)
Lymphoid Tissue (pp. 754–755)
Structure of a Lymph Node (p. 755)
Circulation in the Lymph Nodes
Other Lymphoid Organs
Spleen (pp. 757–758)
Thymus (pp. 758–759)
Mucosa-Associated Lymphoid Tissue
(MALT) (p. 759)
Developmental Aspects of the Lymphatic
System and Lymphoid Organs