Frog Dissection

External Dissection Examine the outside of the frog’s body. Find the mouth, eyes, nictitating membranes, external nares, and tympanum.

Mouth Dissection Turn the frog on its back and cut the hinges of the mouth and open it wide (you may need to crack the jaw open wide with your hands). Identify the following parts: the maxillary teeth, the vomerine teeth, the internal nares, the tongue, the Eustachian tubes, the esophagus, the pharynx, and the glottis.

Internal Dissection Look for the opening between the frog’s hind legs. Begin a vertical incision from this opening toward the mouth. Next, make two horizontal incisions at each end of the vertical one. Completely remove the skin flaps. Make the same incisions through the muscle tissue. Remove and discard this tissue.

Internal Dissection Locate and identify the following digestive organs: esophagus, stomach, small intestine, large intestine, cloaca, liver, gall bladder, and fat bodies. Cut open the stomach and observe its contents.

Internal Dissection Identify parts of the circulatory and respiratory systems in the chest cavity. Find the left atrium, right atrium, and ventricle of the heart. Find the two lungs.

Internal Dissection Use a probe or tweezers to lift the intestines and liver (it may be necessary to remove them to see). Identify the parts of the reproductive and urinary systems. Locate and identify the kidneys, oviducts or testis.