frog procedures
Pithing and Muscle Preparation. The method for pithing the frog and preparing the frog gastrocnemius muscle will be described by the instructor. The object of the pithing operation is to destroy specified parts of the central nervous system. In this case the frog is pithed as a means of immobilization and anaesthesia. Generally, pithing the spinal cord only is adequate.
To skin the frog leg, cut the skin all around the upper end of the leg. Pull the skin down the leg, freeing it from any underlying muscles. The removal of the skin is an operation resembling the removal of a stocking. The skin turns wrong-side out as it is stripped off.
The muscle preparation desired consists of the lower half of the femur bone and the attached gastrocnemius muscle. Other muscles and the tibiofibula should be cut away (note: birds, reptiles and amphibians possess a single bone in the lower leg, the tibiofibula, whereas mammals have separate tibia and fibula bones). Cut the tibiofibula loose by cutting through the knee joint. Retain as much of the Achilles tendon as possible. This structure should be separated from the other tissues around and beneath the heel. Tie a thread securely around the tendon after cutting it free from beneath the heel. The muscle may now be manipulated by holding the femur and/or the thread tied to the Achilles tendon. Keep the preparation moist with Ringer's solution at all times.
The instructor will assist in setting up the stand for mounting the muscle preparation. A femur clamp is attached to the lower part of the stand and the stub of the femur bone clamped in place. The thread from the Achilles tendon is tied to a hook on the variable range force transducer, using as short a length of the thread as possible. Final adjustments can be made by moving the position of the clamps.
Electric connections to the stimulator should be made as shown in the figure below. Good contacts are essential.
Minimal
To skin the frog leg, cut the skin all around the upper end of the leg. Pull the skin down the leg, freeing it from any underlying muscles. The removal of the skin is an operation resembling the removal of a stocking. The skin turns wrong-side out as it is stripped off.
The muscle preparation desired consists of the lower half of the femur bone and the attached gastrocnemius muscle. Other muscles and the tibiofibula should be cut away (note: birds, reptiles and amphibians possess a single bone in the lower leg, the tibiofibula, whereas mammals have separate tibia and fibula bones). Cut the tibiofibula loose by cutting through the knee joint. Retain as much of the Achilles tendon as possible. This structure should be separated from the other tissues around and beneath the heel. Tie a thread securely around the tendon after cutting it free from beneath the heel. The muscle may now be manipulated by holding the femur and/or the thread tied to the Achilles tendon. Keep the preparation moist with Ringer's solution at all times.
The instructor will assist in setting up the stand for mounting the muscle preparation. A femur clamp is attached to the lower part of the stand and the stub of the femur bone clamped in place. The thread from the Achilles tendon is tied to a hook on the variable range force transducer, using as short a length of the thread as possible. Final adjustments can be made by moving the position of the clamps.
Electric connections to the stimulator should be made as shown in the figure below. Good contacts are essential.
Minimal