Pre-AP Biology: Intro to the Fetal Pig Dissection

Why Fetal Pigs The fetal pig is a mammal, like humans. Nearly all major structures are the same or similar in anatomy While there are some interesting differences between pigs and humans, the most important things are very similar. Fetal pigs are not bred for the purpose of dissection, they are a by-product of the pork food industry

Why cont. Fetal pigs are not killed for the purpose of dissection Those that are not used for education will be used for fertilizer production or discarded Most people do not think of pigs as 'pets' Fetal pigs are relatively inexpensive. Even in the extra large size, where structures are well developed, they can be obtained for about 1/3 the cost of a similarly sized cat

Advantages to Dissection Dissection is a hands-on, investigatory kind of activity for students. Dissection allows students to "test the truthfulness" of what they see in books. Dissection impresses on students the normal variation that is present in the natural world. No two fetal pigs, even though they are perfectly normal, will look exactly the same. In fact, to do well on practical, students MUST looks at several examples of each structure in different animals. Occasionally, quite significant anatomical variations will be noticed.

Safety All dissecting tools should be considered dangerous. Notify your teacher immediately if you are cut. Handle probes, dissection scissors, and scalpels with extreme caution. Always cut away from you, never toward yourself or another person. Dissection specimens should be properly mounted in the dissection pan before cutting.

Safety 5. Do not place your hands near your mouth or eyes while handling preserved specimens.  Most of the preservatives in use today are non-toxic to the skin, they may cause minor skin irritations.  If the preservative gets on your skin, wash with soap and warm water. 6. The preservative should never come in contact with your eyes because you will have on goggles. If you remove your goggles and it does, you must wash your eyes (holding them open with hands) in an eyewash or in the sink for 15 minutes.

Safety 7. Inform your teacher BEFORE the lab starts next time if you have any allergy to latex. (This should already be noted on your safety contract) The class will then use vinyl gloves. 8. Wear lab gloves, APRONS, and goggles at all times. 9. Lab gloves and paper towels go in the regular trash.  Skin and pieces of pig go into the separate plastic bag provided by your teacher (not down the sink).

IMPORTANT: Do not rinse off your pig in the sink as you will wash off the chemical that keeps it preserved. What do you think would result?

Dissection Basics dorsal: toward the back of the body ventral:  toward the underside of the body anterior (cranial):  toward the head end of the body posterior (caudal):  toward the tail end of the body

Anterior Posterior Dorsal Ventral

Viewing the Pig Note the thin peeling layer of tissue covering the body of your pig.  This layer is the epitrichium, a layer of embryonic skin that peels off as hair develops beneath it.

Identify the regions of the body: head (cranial) region, neck (cervical) region,trunk region (thoracic region), tail (caudal) region

Determine the sex of your pig: Female:  Look for a single urogenital opening just ventral to the anus.  A prominent genital papilla projects from the urogenital opening.  Male:  Look for the scrotum, a sac-like swelling containing the testes and located ventral to the anus.  The male urogenital opening is faintly visible just posterior to the umbilicus.  Note that males as well as females have multiple nipples = teats = mammary papillae.

Female Male

Responsibility It is your responsibility to respect your pig. It had life and now has the purpose of teaching you mammalian anatomy If you choose to disrespect the pig (if you have to ask, then it is probably disrespect), you also choose to go out side, dig a grave and give the pig a proper burial. You will also choose to be written up and be punished by the principal… Let’s begin dissecting your fetal pig

What to do if you are absent for a dissection day… On your return day, you should ask your lab group to review with you the structures they were assigned to observe that day. Then, you should visit the following website: The Virtual Pig Dissection Homepage at http://www.whitman.edu/biology/vpd/main.html This website is a great resource for absent students. Additionally, it is a great study resource when you are studying for your practical.