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Comparative Medicine

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Veterinarians

Animal Study Proposals

Infectious Disease Pathogenesis

Mouse Necropsy

Necropsy Sheet

Instruments and Fixatives

Necropsy Terms

1) Starter Kit

2) First Incision

3) Lymph Nodes, Mammary Glands

4) Abdominal Cavity

5) Urogenital System

6) Intestines, Stomach, Spleen, Pancreas

Comparative Medicine Branch

Mouse Necropsy

Step 3: The Lymph Nodes and Mammary Glands

Diagram Key

1. Superficial cervical nodes Lymph nodes illustration

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

Lymph Node	Location	Lymph Node	Location
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