The Treasure Hunt of The Elusive Lymph Nodes:
Accept the Challenge if You Dare

Diagram of Lymph Nodes, Thymus, and Spleen

Diagram Key

1. Superficial cervical nodes

2. Deep cervical nodes

3. Mediastenial nodes

4. Axillary node

5. Brachial node

A. Thymus

B. Spleen

6. Pancreatic node

7. Renal nodes

8. Mesenteric node

9. Inguinal node

10. Lumbar nodes

11. Sacral Node

12. Sciatic node

Lymph Nodes

You have reached one of the more frustrating experiences you will ever encounter, trying to find those fun-loving lymph nodes. But alas, those of you who are patient will reap all the rewards of this little exercise. At this point, you are going to be looking for lymph nodes that are located subcutaneously or in the connective tissues between muscles. If there is some type of immune response before the time of the necropsy, it will not be difficult to locate the nodes. On the other hand, if the animal is healthy, wish yourself luck and hope you have good eye sight, because they may be difficult to see. What you are looking for are bead shaped structures about the size of a single grape nut. They can range in color from a yellowish white to tan depending on the strain of the mouse. Obviously, if the mouse is pigmented, the nodes will be darker than that of an albino mouse. Lay the nodes flat on a piece of paper towel and place in fixative. The internal (deep) lymph nodes (see table for locations of selected lymph nodes) lie within the body cavity and can be retrieved at various choice times during the necropsy.

Lymph Node Treasure Map

 Lymph Node


Lymph Node


axillary Armpit popliteal Behind the knee, between the adductor muscle and the semimembranous muscle
brachial Resting on the bicep muscle, underneath the pectorals pyloric (pancreatic) Anterior end of the pancreas, near the pyloric end of the stomach
deep cervical Buried behind the salivary gland renal Between aorta and kidneys
 inguinal Adherent to the skin of the groin sacral Posterior to the bifurcation of the abdominal aorta
 lumbar Anterior to the bifurcation of the abdominal aorta sciatic Below sciatic nerve on back
 mediastinal Thymic region superficial cervical Anterior to the salivary gland
mesenteric Mensentery of the small intestine and pancreas    

Mammary Tissue

Diagram of Mammary Tissue


Diagram A

1. Mammary Gland-Left Cervical

2. Mammary Gland-Left Thoracic

3. Mammary Gland-Left Thoracic

4. Mammary Gland-Left Abdominal

Diagram B

1. Mammary Gland-Left Cervical

2. Mammary Galdn-Left Thoracic

3. Mammary Gland-Left Thoracic

4. Mammary Gland-Left Abdominal

5. Mammary Gland-Left Inguinal

6. Mammary Gland-Right Cervical

7. Mammary Gland-Right Thoracic

8. Mammary Gland-Right Thoracic

9. Mammary Gland-right Abdominal

10. Mammary Gland-Right Inguinal

Also, at this time you may wish to examine the mammary tissue of the animal. If the animal is pregnant or lactating the tissue is readily identifiable. It will look as if cottage cheese has been placed between layers of epithelium on the internal surface of the skin. If your animal is not "in the family way" but still looks like mascot for the dairy industry, there might be a pituitary lesion to blame. A nonpregnant, nonlactating, or male mouse should not have a great deal of visible mammary tissue. In those genetic manipulation studies aimed at studying mammary tumors, the tumors will be quite obvious clincially.

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Site designed, written, and selected pictures illustrated by Erin Parsoneault, inspired by D.E.Devor-Henneman, and edited/mentored byDr. J.M.Ward