The lymphatic system collects and cleanses the fluid which seeps out of the capillary beds, bathing the tissue which it perfuses. This cleansing fluid, called lymph, is collected by afferent lymph vessels which carry it to a lymph node where it is filtered. There, macrophages consume bacteria and debris, and immune cells monitor the lymph for antigens which might react with their antibodies and stimulate them to multiply and make antibodies. The cleansed lymph leaves via an efferent lymph vessel.
In the abdomen, cleansed lymph from the intestines is collected in the cysterna chyli, and, except for the upper R quadrant of the body, is collected into the thoracic duct which empties into the circulatory system through the L subclavian vein. (The upper right quadrant drains by the R lymphatic duct into the R subclavian vein.)
[Gilbert has no relevant illustrations.]
ANATOMY: Illustrate the highlighted features of the lymphatic system in the cat:
The hepatic portal system has been injected with yellow latex, showing the venous drainage from the intestines to the liver.
The lymphatic drainage follows the same pattern as the arterial (red) and venous drainage sytems (yellow in the case of the hepatic portal system). Examine the relationship of the mesenteries to the small intestine in the dissected cat.
[Thanks to Professor Brian W. Witz at the Nazareth College of Rochester for correcting identifications of some of the features of the lymphatic system on this page.]
Small afferent lymph vessels (difficult to see) lead to lymph nodes. Once filtered, lymph is carried by the efferent vessels which empty into the cisterna chyli, located behind the abdominal aorta.
As the cisterni chyli passes through the diaphragm, it becomes the thoracic duct. In the thorax, it may be seen as a thin brown tube to the left of the aorta, under the parietal pleura and the intercostal arteries.
Trace the throacic duct up until it passes behind the left subclavian vein into which it empties (next to the jugular vein).
Note also these lymph nodes:
the submandibular (and another view of both the R and L submandibular lymph nodes.)
the numerous lymph nodes associated with the ileocecal junction .
HISTOLOGY OF A LYMPH NODE:
Examine and illustrate the following slide, labeling the specified features. Note the function of each feature. It is specially stained with silver and gold to show reticular fibers. The plate numbers are in the 9th Ed. of di Fiore’s Atlas of Normal Histology:
Slide 3. Lymph node, Reticular tissue, (H 550) VE: p. 125 & 127, 40x:
At 100x, one can see the subcapsular sinus more clearly and the medulary sinus is at the bottom of the image.
At 400 x, details of the capsule become clearer.
Note the space under the capsule, the subcapsular sinus , which contains the lymph within the node.
A close-up of a germinal center:
trabeculae form baffles which direct lymph over the germinal centers
germinal centers house immune cells, enlarge during infections
[Here is a labeled version of the image.]
medullary sinus chamber (s) in the center, collects filtered lymph
reticular fibers give structure to the gland, anchor macrophages, (best seen at 400x)
Here are additional images similar to the ones above, but with slightly different views.