Setup for the Dissection
Frog Dissection for Biology 110
Penn State Altoona Biology
Penn State Altoona
3000 Ivyside Park
Altoona, PA 16601-3760
III.) Setup for the Dissection
Preparation:
This section explains the steps necessary to prepare your frog for the
dissection process.
1. Place Frog in Pan
Rinse the frog with water then place it in the dissection pan. The frog should be lying on
it's dorsal (back) side with the belly facing up.
2. Pin the Frog
Pin the frog for dissection by securing each of the four limbs to the pan. Place the pins
through the hands and feet to secure them to the pan.
3. Begin the First Skin Incision
Once the legs of the frog are securely pinned to the dissection tray begin the first skin
incision by using the forceps to lift the skin midway between the rear legs of the frog.
Using the scalpel, make a cut along the center, or midline, of the frog, bisecting it
equally.
4. Continue the Skin Incision
Continue the skin incision by using the scissors to cut all the way up the frog's body to
the neck. Be very careful not to cut too deeply.
5. Make the Leg Incisions
Still using the scissors, make horizontal incisions just above the rear legs and between
the front legs of the frog.
6. Separate the Skin & Muscle
Once you have finished the incisions between the front and rear legs of the frog you need
to separate the skin flaps from the muscle below. To do this:
Pick up the flap of skin with the forceps, and
Use a scalpel to help separate the skin from the muscle below.
7. Pin Skin Flaps
Once the skin flaps have been cut pin them to the dissection tray using several pins.
8. Begin the First Muscle Incisions
This section will describe the procedures for making the incisions through the frog's
abdominal muscles.
Now that the skin has been removed, begin the abdominal muscle incision by using the forceps to lift the muscle midwy between the rear legs of the frog. Next use the scalpel to start the incision in the direction of the chin.
9. Continue the Muscle Incision
Using the scissors, carefully continue the incision up the midline of the frog, but do not
cut too deeply as to damage the organs.
10. Turn Scissors Blades
This is very important. When you reach a point just below the front legs, turn the
scissors blades sideways to cut through the bones in the chest. This should prevent damage
to the heart or other internal organs. When your scissors reach a point just below the
frog's neck you have cut far enough.
11. Make the Second Muscle Incisions
Next, using the scissors, make horizontal incisions through the muscle between both the
front legs and above the back legs.
12. Separate Muscle & Organs
To finish opening up the frog's body cavity therefore exposing the abdominal region, use
the forceps to hold the muscle flaps while separating the muscle from the tissues below
with a scalpel.
13. Pin the Muscle Flaps
Once the muscle flaps have been separated from the underlying tissue, they must be pinned
back. This will allow easy access to the frog's internal organs.
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