The arteries have been filled with red latex and the veins with blue. An incisi
The arteries have been filled with red latex and the veins with blue. An incision was made on the side of the neck to enable the injections. The incision can be seen in the first photograph below.
Several different pig dissections were used to obtain the photographs below. As a result, a structure shown in one photograph may look different than the same structure shown in another photograph.
Click on any of the photographs to view enlargements. Links to high-resolution, unlabeled photographs are also provided for many of the photographs.
Orientation
The following words will be used to help identify the location of structures.
- Anterior refers to the head end. If a structure is anterior to another, then it is closer to the head.
- Posterior refers to the tail end.
- Dorsal refers to the back side. The pig in figure 1 is lying on its dorsal side.
- Ventral is the belly side. It is opposite the dorsal side. The pig in figure 1 below has its ventral side up.
External Structures
Obtain a fetal pig and identify the structures listed in figure 1. Use figures 1–4 below to identify its sex.
The word “urogenital” refers to an opening that serves both the urinary (excretory) and the reproductive systems.
Preparation and Initial Cuts
Tie one front leg of the animal with a string that passes underneath the dissecting pan to the other leg. Repeat this with the back leg.
Insert one blade of scissors through the body wall on one side of the umbilical cord and cut posteriorly to the base of the leg as shown in figure 6. Continue cutting from the anterior end of this cut so that it resembles an upside-down U. Your finished cut will be anterior to the navel and along each side of the navel. The flap of the body wall that contains the navel can be folded posteriorly to reveal the internal organs of the abdomen.
Extend a single cut along the midline of the ventral surface of the animal to about 2 cm. from the chin. Cut completely through the body wall in the abdominal area but keep the cut shallow in the neck region.
A cut is made on the side of the animal from the point just posterior to the diaphragm dorsally. A similar cut is made on the other side. These two cuts will enable you to spread open the abdominal cavity.
Mouth and Neck Region
Use a scalpel to cut the sides of the mouth so that the bottom jaw can be opened for easier viewing (see figure 11). You will need to cut through the musculature and the joint that holds the lower jaw to the skull.
Open the jaw wide enough so that the glottis and epiglottis are exposed. The epiglottis projects up through the soft palate into a region called the nasopharynx. The hard palate and soft palate separate the nasal and oral cavities. When breathing, air passes through the nasal passages to the pharynx. The pharynx is the space in the posterior portion of the mouth that both food and air pass through. From the pharynx, it passes through the glottis to the trachea.
Carefully, peel the skin away from the incision in the n