Virtual Mouse Necropsy
Step 8: Lobes of the Liver 2 - Diagram of Sternum Removal
Preparation
First, to get to the liver, you must remove the sternum. Lifting up the sternum with your forceps, puncture the diaphragm and cut along each side of the sternum up through the cervical girdle ( follow the dotted lines in the diagram). Be careful to keep the points of your scissors pointed upward in order to prevent any damage to the thoracic organs underneath. For example, the thymus occasionally has the tendency to cling to the dorsal side of the sternum. Preserve the sternum if you wish to perform any bone marrow examinations, as it is a good bone for this purpose. Next, sever the vena cava on the thoracic side of the liver and pull the esophagus through the liver in the anterior direction.
Removing the Liver
You now have to cut the diaphragm out in order to remove the liver. Using the diaphragm as a handle, start pulling the liver out of the abdominal cavity until you feel some resistance. This is caused by the hepatic artery. Cut the hepatic artery, being careful not to prematurely liberate the right adrenal. If you intend to weigh the liver, rinse and drain it of excess blood.
Liver Lobes
Depending on your protocol, you will take different lobes. You have a four-lobed liver. There is a median lobe, a left lobe, a right lobe, and the caudate lobes (see diagram). The gall bladder is hanging in the little bifurcation of the median lobe. If this is of particular interest to you, leave it where it is and request to have it sectioned by the histology people. Separate the lobes from each other at the junctions, examine for any lesions, and place in fixative. Fixing the liver whole will not permit the fixative to penetrate, which will ruin your project. Please spend the few extra seconds needed to separate the lobes before fixation.
Liver Trimming Protocol
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