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Pig Dissection
Introduction
The fetal pig, Sus scrofa, belongs to the phylum Chordata, Class mammaila, Order Artiodactyla,
genus Sus, and species scrofa. The fetal pig is an excellent animal for dissection purposes due to
its resemblance to a human.
Teamwork
A dissection is like an operation and requires teamwork. Your team will consist of:
1. Surgeon- person who physically makes incisions with the scalpel and forceps.
2. Assistant surgeon- assists the surgeon.
3. Reader- Reads instructions and directs the surgeon.
4. Recorder- Draw and label during the dissection.
Materials
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A large dissection cutting board
String
Surgical scissors with one blunt tip
Scalpel
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Dull probes
T- Pins for holding down the skin flaps
Forceps
Ruler
Care for Your Pig
At all times during the dissection it is essential that you show respect for your animal. It is also
important that your specimen is sprayed with Bioshield before placing it back in the plastic bag
for storage, this will
prevent the tissue from
drying out or becoming
moldy.
Dissection skills
Dissection is a learned
skill. Some general rules to
remember are: do not make
deep cuts with scissors or
scalpels;
you
may
inadvertently
damage
underlying tissue. Know
the anatomical terms such
as caudal, cranial, dorsal,
ventral, medial, and distal
so that you can follow the
directions as you study
your organism.
How to Begin: Day 1
Draining the Organism
1. The “surgeon” and “assistant surgeon” need to put on gloves. Meanwhile, the “recorder”
needs to have your storage bag labeled with your names and period.
2. Open the bagover the sink, and carefully allow fluids to drain into the sink. Holding the
pig with two gloved hands, rinse pigs thoroughly under running water. Place pig onto
dissecting board.
External investigation
1. Place pig stomach down. Make a sketch and label the major structures: Pinna-Ears,
Nares-Nostrils, Eye, Anus, Urogenital opening, Mammary Papillae-nipples,
Umbilical cord.
a. Is your pig a female or a male? _______________________
In male fetuses, the urogenital opening is located just caudal from the umbilical cord.
You should also find a scrotal sac just proximal to the umbilical cord. In females the
urogenital opening is just ventral to the anus.
b. What is the purpose of the umbilical cord? __________________________________.
Pig Dissection
Superficial Muscles
1. You will skin the front right leg, front right
shoulder, right side of the chest, and the back
exposing the muscles of the shoulder, leg and
back. Shallowly cut around the distal end of
the front right leg. Shallowly cut around the
neck. Make an incision through the skin at the
base of the neck, between the two ears, along
the dorsal ridge to the center of the back. Make
an incision from under the armpit up to the
incision that you made on the back. Make an incision from the neck down to the center of
the chest. Carefully remove the skin covering the front right leg, and shoulder.
2. Draw and label the Trapezius, Deltoideus, Latissimus dorsi, and Triceps long head.
Internal Investigation: You will not remove organs at this time
1. Place your pig on its dorsal side. Secure your pig by tying a length of string to one limb
and pass it under the cutting board and tie it to the opposite limb tautly. Repeat with the
other limbs.
2. At the umbilical cord, make an incision through the body wall just deep enough to cut
through the muscles. Cut around the umbilical cord. Make an incision across the chest
from one armpit to the other. Make an incision across the belly just above the umbilical
cord. Make a connecting incision that starts from the chin, goes across your chest
incision, all the way down to your belly incision, opening up the respiratory and digestive
cavity. Pull back the flaps and identify all the organs on the yellow side of the accessory
“Fetal Pig Dissection Guide”.
End of Day One:
Make sure that your instructor sprays your specimen with Bioshield for preservation purposes.
Place your pig into plastic bag and seal. Place dissecting tools, sharp end down into cleaning
solution. With soap and water clean the dissection tray.
Beginning of Day Two
Internal Investigation: Identifying and removing internal organs
Dissecting out the Respiratory System and the Heart
1. Secure your pig with the string wrapped around the cutting board as you did before.
2. Begin by identifying and removing the thymus gland. The thymus is a grayish mass that
rests just ventral to the heart. The thymus is where T-Cells mature and learn to tell self
from non-self. The assistant surgeon should keep removed organs organized.
3. Identify the trachea and the larynx (voice box). Also identify the thyroid gland that sits
near the larynx. The thyroid gland produces triiodothyronine (T3) and thyroxine (T4),
which are “steroid like” hormones that increase the metabolic rate of all the cells in the
body. Follow the trachea from the oral cavity down to the lungs. The right lung has four
lobes and the left lung has three.
4. The heart, covered by the pericardial sac, sits between the lungs. Remove the pericardial
sac and carefully pull back the lungs so that you can identify the aorta and the vena cavas.
5. Carefully remove the trachea, snip near the throat, the lungs, and the heart. Cut through
the vena cavas and the aorta to remove the heart. Do not take out the esophagus, which
sits just behind the trachea.
Bisect the Heart
1. With the scalpel, bisect the heart, draw and
label.
2. The Heart and Respiratory system are located in the thoracic cavity. Notice how the
thoracic cavity is separated from the abdominal cavity by the diaphragm. Also notice how
the esophagus, aorta, and caudal vena cava pass through the diaphragm and membranes
separating the thoracic and abdominal cavities.
Pig Dissection
Removing the Digestive System
1. Use your scissors to cut the joints on both sides of the mouth. Observe the teeth, tongue,
hard palate, and soft palate. The hard palate separates the mouth form the nasal cavity.
The soft palate is just caudal to the hard palate.
2. How many teeth do you observe?______
3. Observe how the esophagus connects the throat to the stomach. You will need to cut
through the membranes that hold the intestines in place.
4. Look underneath the liver to find the Gall Bladder.
5. Draw and label the connection between the pancreas (grayish in color), the bile duct, and
the small intestine. This should be close to where the stomach connects to the small
intestine. This portion of the small intestine is called the duodenum.
6. Remove the liver. How many lobes does it have?______ What are three functions of the
liver?_______________________,___________________,&_____________________
7. Although not part of the digestive system, the spleen will be found underneath the
stomach. The spleen filters the blood to remove old red blood cells. Remove this organ
now.
8. Carefully remove the entire digestive tract at this time. Be sure not to remove the
kidneys. You will be removing the esophagus, the stomach, the small intestine, and the
large intestine. Leave an inch or so of the rectum. Notice the cecum, small finger like
projection where the small intestine and the large intestine meet. This functions to digest
plant material.
9. Once removed, measure the length of the entire digestive tract. How long is it?________
10. Is there anything in the digestive tract? Why or why
not?____________________________________________________________________
________________________________________________________________________
________________________________________________________________________
End of Day Two:
Make sure that your instructor sprays your specimen with Bioshield for preservation
purposes. Place your pig into plastic bag and seal. Place removed parts in a separate smaller
bag. Place dissecting tools, sharp end down into cleaning solution. With soap and water
clean the dissection tray.
Beginning of Day Three
Urogenital System
1. Extend the incision from the caudal side of the umbilical toward the tail. Open up the
urogenital system as shown in the following diagrams. Depending on the sex of your
specimen, either use figure six or seven to identify the following organs.
Pig Dissection
2. Draw and label the urogenital system of your pig.
3. What are the functions of:
a. Kidneyb. Uretersc. Urethrad. Urinary bladdere. Ovariesf. Oviductg. Uterush. Vaginai. Scrotumj. Testes-
Nervous System
1. Remove the skin and tissue from the dorsal half of the head until the skull is exposed.
Start at the base of the skull, in the occipital region, and carefully chip away the bone
revealing the brain. Work until the entire brain is exposed. The brain is covered by three
membranes, or meninges. Very carefully remove the meninges so that you may see the
folds of the cerebral cortex. Diagram what you see. Be able to recognize the cerebrum,
the longitudinal fissure that separates the cerebral hemispheres, the cerebellum, and the
brain stem or medulla oblongata.
Clean-up
Place your pig into plastic bag and seal. Place removed parts in a separate smaller bag. Place
dissecting tools, sharp end down into cleaning solution. With soap and water clean the
dissection tray.
Day 1
Surgeon_________________
Asst. Surg._______________
Reader__________________
Recorder________________
Day 2
Surgeon_________________
Asst. Surg._______________
Reader__________________
Recorder________________
Day 3
Surgeon_________________
Asst. Surg._______________
Reader__________________
Recorder________________