In the old days, advanced science students would be required to put down their frogs themselves, using chemicals. While this resulted in fresh frogs for dissection, the practice is pretty rare nowadays. For the most part, you’ll get frogs that have been dead for quite some time.
If you’re not comfortable dissecting a frog in class, tell your teacher. Digital alternatives are common.
If the specimen is female, keep an eye out for eggs and enlarged ovaries, which may need to be removed before you can identify certain organs.
The external nares are the technical term for the frog’s nostrils, which are used for breathing and should be far forward, above the mouth opening. Each tympanum is located behind the eyes, and is a flattish round spot used for sensing sound. [2] X Research source
The eustachian tubes are to the left and right of the back of the throat, and are used to equalize pressure. The vomerine teeth are behind the maxillary teeth, though both are used to secure prey and keep it secure in the mouth.
Cutting open the torso with an “H” pattern is also common. To do this, make transverse (horizontal) cuts just inside the arms and legs, and connect them with a lateral cut up the belly. This should create two hefty flaps that you can pull back and open the frog, pinning them to the tray if necessary. [3] X Research source
For the most part, you won’t want to remove the organs until you’ve identified them. They can help to keep an accurate portrait of the anatomy, finding other organs in relation to what you’ve already identified. Follow the instructions of your lab instructor, however, and remove them when it comes time to do so.
Follow the small intestine to the large intestine. The large intestine, also known as the cloaca, should widen at the bottom of the small intestine. This is where waste exits the body of the frog.
If it is part of the project, use your scalpel to carefully open the stomach with a small horizontal cut. Keep your face up and away, in case any spitting occurs. What seems to be inside? You might notice bile or even some partially digested food.
You probably won’t remove any organs from the frog at this point in the process. You should have removed everything necessary to locate and identify all the organs in the frog, making removal unnecessary.
If you’ve got a male frog, the testes should be at the top of the kidneys. They should be pale and round. If you’ve got a female frog, find the oviducts. There should be a curly structure outside the kidney, where female frogs produce eggs.
It may take some work to get the smell of the preservative off of your hands, so you may want to return to them after a couple hours for another scrubbing.
