Fetal Pig Dissection

Day 1 - External Anatomy & Oral Cavity

The dissection of the fetal pig in the laboratory is important because pigs and humans have the same level of metabolism and have similar organs and systems. Also, fetal pigs are a byproduct of the pork food industry so they aren't raised for dissection purposes, and they are relatively inexpensive.

External Anatomy

The gestation for the fetal pig is 112-115 days (almost 4 months), but a fetal pig has not been born yet. However, its approximate age since conception can be estimated by measuring its length. Measure your pig's length from the tip of its snout to the base of its tail.

Record the pig’s length on your study guide. Use the length/age chart on this sheet to determine the age of your fetal pig and record its approximate age on your study guide.

Examine the sense organs located on the pig's head. Locate the eyelids, ears, and nostrils.

Determine the sex of your pig by locating the urogenital opening through which liquid wastes and reproductive cells pass. In the male, the opening is on the ventral (stomach) surface of the pig just posterior (behind) the umbilical cord. In the female, the opening is below the anus. Record the sex of your pig.

Oral Cavity Using your dissecting scissors, cut through the jawbones at the corner of the pig's mouth. Cut far enough so that the bottom half of the jaw can almost touch the pig's chest.

Open the mouth as far as you can. Use the labeled picture to identify the papillae (taste buds) on the edges of the tongue, the ridged hard palate in the roof of the mouth with the smooth soft palate behind it, the sharp teeth near the front of the mouth, and the epiglottis, which is a flap of tissue that covers the opening of the trachea (windpipe) so food cannot enter the airway and cause you to choke. Find the area called the pharynx at the back of the throat and nasal cavity. Air enters an adult pig through the mouth or nose before passing through the pharynx and down the trachea to the lungs. Answer the questions and label the diagram of the Oral Cavity on your Day 1 Study Guide. Complete Buddy Check!

Day 2 – The Abdominal Cavity

Study the diagram below. The dashed lines numbered 1-5 show the incisions you will be making today. With scissors, make the incisions in order, beginning with 1. Be sure to keep the tips of your scissors pointed upward because a deep cut will destroy the organs below. Also, remember to cut away from yourself. Spread the flaps of the body wall apart and pin them to your dissecting tray. Cut the umbilical vein, which extends through the liver. Locate the diaphragm, a sheet of muscle that separates the abdominal cavity from the thoracic (chest) cavity. The two dominant organ systems located below the diaphragm are the digestive system and urinary system. Find the most obvious structure in the abdominal cavity, the brownish-colored liver. Count the number of lobes (sections) of the liver. The liver is responsible for storing nutrients, producing bile, and filtering toxins out of the body. Lift the liver to view the gallbladder, a greenish duct located under the liver. The gallbladder stores the bile produced by the liver and releases the bile into the small intestine for chemical digestion. Carefully place your scissors between the diaphragm and the top of the liver and remove the liver in order to view the rest of the digestive system. Find the spleen, a long, reddish-brown organ wrapped around the stomach. The spleen filters out old red blood cells and produces new ones for the fetus.