Digestive System Dissection of the Fetal Pig

Thoracic Region

See the diagrams and/or picture file(s) to help locate the following

1. Cut the diaphragm away from the body wall on both sides of the pig.
2. Force the thoracic cavity open with your fingers to expose the lungs and heart.
3. Breaking the ribs with your fingers may help keep the cavity open.
4. The lungs appear as solid bodies since they do not contain air in the fetus.
5. Locate the trachea, a white tube with rings of cartridge ((bendy( straw feature) which air travel through to the lungs.
6. Continue up the trachea until you reach the sound producing voice box or larynx.
7. Take a blunt probe and look beneath the trachea to find the esophagus, the tube that leads food from the mouth to the stomach.

Abdominal Region

See the diagrams and/or picture file(s) to help locate the following

1. Make a pair of lateral incisions through the body wall on each side in front of the hind legs to expose the abdominal cavity.
2. Optional: If you have a lot of brownish-red coagulated blood, wash out the abdominal cavity with tap water to remove the coagulated blood.
3. When examining the viscera (soft internal organs) with your fingers, be careful not to tear any of the structures. The body cavity (coelom) in which the thoracic and abdominal organs are located is completely lined with an epithelial layer called the peritoneum. Organs are also covered with a layer of peritoneum. A double layer of peritoneum is called a mesentery. Mesenteries serve to suspend and hold structures together and are clear in appearance.
4. Once you have opened the abdomen and washed out the cavity.
5. The most obvious structure in the abdominal cavity is the liver. The liver is composed of 5 lobes which are attached only at the dorsal and anterior margins. The gland makes bile and stores excess glucose or blood sugar.
6. Posterior to the liver are the small intestine, where food is mostly broken down and nutrients are absorbed, and the thicker greenish coiled large intestine (colon), used to mainly absorb water. The small and large intestines are suspended from the mid-dorsal body wall by mesentery.
7. Carefully lift and push the small intestine forward and find where the posterior part of the small intestine enters the large intestine (hint: look for a little pointed knob-like or dead end structure called the cecum to help show you where the junction is). Our cecum extends to become our appendix.

8. Put the intestines back in their normal positions and lift the liver forward to see the soft, white-walled stomach anterior to the intestines. The stomach helps to hold and slightly breakdown food.
9. The dark-colored lag-like spleen is located along its left posterior border and attached to the stomach by peritoneum. The spleen helps to destroy and recycle old red blood cells.
10. A light-colored granular structure (applesauce texture), the pancreas, is found in the mesentery between /below the stomach and the first portion of the small intestine. The pancreas helps produce insulin to help maintain proper sugar levels in the blood and secretes digestive chemicals into the small intestine.
11. The gall bladder, used to store a chemical called bile which is used to separate fats in food in the small intestine, may be seen by lifting up the extreme right lobe of the liver. It appears as a small upside down, light white/green/brownish sac under the lobe. The duct from the gall bladder, the bile duct, opens into the duodenum (first portion of the small intestine). The pancreatic duct also opens into the duodenum at about the same location as the bile duct. It may be nearly impossible to find and trace the path of these ducts in your fetal pig, just try your best here.
12. Locate the muscular diaphragm, which separates the abdominal and thoracic cavities. The diaphragm is a muscle used for breathing, when it contracts a lower atmospheric pressure within the thoracic cavity occurs. Air, having a higher pressure, enters the lungs by this method by rushing into the lungs.