Michelle Sukup
Loyal Lassies/Ingraham Straight Shooters
Animal Science
Over a period of three weeks, I dissected a fetal pig.
I obtained the pig from Nebraska Scientific, a specimen supplier, for $28.
The pig was shipped preserved in fluid, so all I had to do to keep it preserved
was to return it to the fluid after each session. To be sure my pig would
be okay, I stored it in a refrigerator between dissections. I did not dissect
the fetal pig as part of a class, I did it on my own before and after school,
that is why it took me so long to finish it. By doing it on my own, I had
to work out of books, without the aid of a teacher, but if I needed help,
I knew that there would be someone willing to get their hands dirty. I
frequently had visitors wanting to know where that awful smell was coming
from, so I answered questions and let them play around with the pig if
they felt inclined to do so.
Things to remember:
Wash
hands after handling the pig. It may be preserved in formaldehyde, which
can be toxic and damage your eyes. In addition, the smell on hands will
be very strong if not scrubbed adequately, even if gloves were worn. Dissect
in a well-ventilated area because the smell can be overpowering.
Have
a dissection kit that includes scissors, tweezers, a scalpel or two, tweezers
and pokers. Straight pins and string are also helpful. Be careful with
sharp instruments, and be sure that your instruments are sharp, otherwise
it is difficult to cut, and dull instruments may damage the systems.
Dispose
of the pig properly: if your school, or wherever you are dissecting, does
not have a program set up to dispose of the animal, seal it in the original
bag and put it in the dumpster.
| Cm | In | Approximate age (days) |
| 1.1 | .433 | 21 |
| 1.7 | .669 | 35 |
| 2.8 | 1.01 | 49 |
| 4.0 | 1.57 | 56 |
| 22.0 | 8.66 | 100 |
| 30.0 + | 11.8 | Full term 112-115 |
My first step was to measure the pig to establish its
age. My fetal pig was approximately 38.7 cm, which means that it is a full
term pig, approximately 112-115 days old. The scientific name of the domestic
pig is sus scrofa, which is the same species as the European wild
hog.
The pig had been shipped curled in the fetal position,
so I had to tie the legs down to adequately expose the ventral surface.
I then made incisions along the forearms, up the middle of the neck, at
the edge of the jaw and neck, down the midsection, and down the legs. These
incisions only cut the skin and the fascia (the layer of connective tissue
around muscles and muscle groups). One must be careful not to cut too deeply
at this point otherwise the muscular systems will be damaged.
My next step was to remove the pig’s skin. With the skin
off, I could identify different muscle groups such as the pectoralis major
across the chest, and the latissimus dorsi along the sides next to the
pectoralis minor, which lies in the caudal direction next to the pectoralis
minor.
This view offers a better look at the pectoralis major
and the latissimus dorsi as well as the pectoralis minor.
This is the thoracic cavity. To expose these organs, one
must cut through the sternum with a pair of scissors. Scissors are the
most helpful tool when dissecting. This is a close up or the thoracic cavity.
In this view, one can easily see where the diaphragm is. Before it was
cut, it was attached to the ribs and formed a barrier between the thoracic
and the abdominal cavity.
This is the lower abdominal cavity. When dissecting this
part of the animal, it is important to go slowly because the tissue is
fragile and if certain organs (the stomach and intestines) are accidentally
cut, they can ooze liquid that makes other organs hard to see.
I am holding part of the small intestine (some of it ripped
when I removed it and some remained in the pig.) I am 5’4", and the chair
is 18 inches off the ground. When measured, the small intestine was 8 feet
4 inches long.
This is the oral cavity. To open the mouth this wide, one must cut the bones of the jaw where the mandible and the maxilla meet. It is best to do this with scissors. This was difficult, but with a little strength, it was manageable.
The next system explored was the nervous system. To expose the brain, one had to break the skull off in little bits with tweezers. The skull was the hardest bone I encountered in the body. If too much is broken off at a time, it may damage the brain. The brain is covered by a thin layer of protective tissue that gives it its shape and appearance of folds.
This is another view of the brain.
This is the ventral view of the brain and vertebrae.
