Fetal Pig Dissection
Remember that you are responsible for the clean up after each period.
The objective of this investigation is to develop an appreciation for how all the organ systems of the body are connected physically, each working together to maintain homeostasis. Each day you will locate the structures indicated in the checklists below and answer the follow up questions posed. If you wish to remove a structure, ask permission first and then do so for further viewing and cutting. Become familiar with the anatomical terms provided for they will be referred to frequently. Also be sure at the end of your dissection you can list all twelve endocrine glands. Evaluation (/50) is based on dissection technique (/10), which includes daily attendance, the questions to be handed in each day at the start of class (/20) and informal interviews (/10) held each day to test your knowledge and awareness.
Day 1 FOCUS - External Anatomy, Digestive and Respiratory Systems
Before any cuts are made, identify each of the structures below.
skin eye (nictitating membrane)
external nares (nostril) ear
genital papilla umbilical cord
toes
THE DISSECTION
You will be making ventral/medial incisions creating flaps in the abdomen & thorax. Cut 1 cm around the umbilical cord down to a point 5 mm anterior to the scrotum or genital papilla. With a piece of string tie the umbilical cord before it is cut & lost.
Answer the following questions:
1. What ethical and moral issues arise from this kind of investigation?
2. What is the purpose of our dissection?
3. How is the fetal pig preserved?
4. In what anatomical position do we dissect and make our first incisions on the pig?
5. What is the first structure observed after the first cuts and openings are made?
Observe the following structures. Once identified place a in the box.
DIGESTIVE RESPIRATORY
tongue, teeth lungs (do cross section of a lobe)
salivary glands (head area) trachea
esophagus bronchial tube, bronchi
stomach pharynx (inside space)
small intestine larynx
large intestine, colon thyroid, parathyroid
rectum thymus gland
liver, gall bladder
pancreas
Answer the following questions:
1. Which structures above are endocrine glands?
2. What releases insulin? What stores bile secreted by the liver?
3. What is proximal to the trachea?
4. What is located in the lungs?
5. What role does the thyroid play?
Day 2 FOCUS - Circulatory and Urogenital Systems
Observe the following structures. Once identified place a in the box.
CIRCULATORY
Note: Arteries are injected with red latex while veins are injected with blue latex.
heart - atria, ventricles, coronary vessels, septum, aorta
(You may remove the heart for a cross section)
venous system (precava, postcava)
pulmonary arteries/veins
UROGENITAL Female Male
kidney (make a cross section) ovary penis
renal artery/vein fallopian tube testes, scrotum
pelvis and ureters uterus epididymis
urinary bladder, urethra vagina vas deferens
Answer the following questions:
1. Which structures above are endocrine glands?
2. What hormones do the ovaries and testes release?
3. Why is the placenta considered an endocrine gland?
4. What are the 3 main sections of the kidney? Draw a cross section.
5. Where is the adrenal gland located?
Day 3 FOCUS - Nervous System – Brain and Spinal Cord
In order to identify this system place the pig dorsally on the dissection tray and make an incision on the back of the animal to reveal the spinal cord and associated nerves. Observe the following structures. Once identified place a in the box.
spinal cord
medulla oblongata
brain - obtain permission to attempt a dissection, use the instructions below
Make a longitudinal cut through the skin and muscles of the head on the dorsal side from the base of the snout to the base of the skull. From the longitudinal incision, make a transverse cut ventrally to the angle of the jaws in front and similar cuts at the caudal end of the longitudinal incision to a level just ventral to the ears. Remove the skin and muscle to expose the skull.
cerebellum medulla
cerebrum pituitary gland
pons thalamus, hypothalamus
Answer the following questions:
1. What attaches to the medulla oblongata connecting the spinal cord to the brain?
2. Describe the brain.
3. What is the white mass that can be seen in the cerebral hemispheres?
4. What glands can be found in the brain that secretes hormones?
5. What hormones are released from the pituitary gland?