Virtual Mouse Necropsy
Step 3: The Lymph Nodes and Mammary Glands
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
Trying to find the lymph nodescan be a frustrating experience. Succeeding requires patience. 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, 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 mouse. If the mouse is pigmented, the nodes will be darker than those 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 times during the necropsy.
Lymph Node Treasure Map
| 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 the 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 the sciatic nerve on the back |
| mediastinal |
Thymic region |
superficial cervical |
Anterior to the salivary gland |
| mesenteric |
Mensentery of the small intestine and pancreas |
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Key
Diagram A
1. Mammary Gland-Left Cervical
2. Mammary Gland-Left Thoracic
3. Mammary Gland-Left Thoracic
4. Mammary Gland-Left Abdomina 
Diagram B
1. Mammary Gland-Left Cervical
2. Mammary Gland-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
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