| Figure 1. The Lymph node. (CLICK
ON THE DIAGRAM ABOVE to see EM of FDCs; To return to the
syllabus CLICK on your browser's back button) The
pink layer beneath the capsule (CAPS) and subcapsular sinus
(SS) is the cortex (C) and it contains the secondary lymphoid
nodules. Each nodule is shown with a germinal center which
has a light (L) and a dark (D) zone. Beneath the cortex
are located two paracortical (or deep cortical) units (DCU;
blue). These bulge toward the medulla. The medulla is composed
of the medullary cords (MC) and the surrounding medullary
sinuses (MS). Additional abbreviations: AFF, afferent lymphatics;
EFF, efferent lymphatics; A, artery; V, vein; PCV, postcapillary
venule; T, T-cells; B, B-cells; IDC, interdigitating dendritic
cells; PC, plasma cells; MO, macrophages. |
6.
VASCULAR RELATIONS: (See Fig. 1. above)
a.
Lymphatic Vessels and Sinuses
In the direction of the flow of lymph these are:
(1) Afferent
lymphatic vessels, which drain the interstitial fluid
from the surrounding tissues, enter the capsule
obliquely (through valves, which prevent back flow) and open
into the
(2) Marginal (= subcapsular) sinus;
the lymph, containing cellular elements flows into the
(3) Intermediate sinuses along the trabeculae
in the cortex and either directly, or indirectly through the
torturous
(4) Medullary sinuses it leaves the node
through valves via the
(5) Efferent lymphatics. (The "filtered"
lymph is eventually emptied into the venous blood via the
Thoracic duct or the Rt. Lymphatic
duct.)
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