The experimental method was obtained from the official website of the Fourth Military Medical University
Operation method
Experiments on the preparation of sciatic nerve-gastrocnemius muscle specimens from frog or toad
Principle
Some basic life activities and physiological functions of amphibians such as frogs or toads are similar to those of warm-blooded animals, while the living conditions of their isolated tissues are easy to grasp, and the neuromuscular specimens can remain physiologically active for a longer period of time under the infiltration of Ren's fluid. Therefore, isolated specimens of the sciatic nerve gastrocnemius muscle of frogs or toads are often used in physiology experiments to observe the excitability of neuromuscular excitability, excitatory process, and the characteristics of contraction of the skeletal muscles.
Materials and Instruments
Frog Move (1) Destroying the cerebral spinal cord: take a toad and rinse it with tap water. Hold the toad with the left hand, press the front of the head with the forefinger so that the head is bent forward, the right hand holds a frog-pricking needle from the occipital foramen forward into the cranial cavity (Fig. 1), stirring the right and left to destroy the brain tissue, and then the frog-pricking needle is backed up to the occipital foramen, and instead of pulling it out, the tip of the needle is turned backward and inserted into the spinal canal to destroy the spinal cord, and the toad's hind limbs lose their tensile strength when inserted into the vertebral canal and urinary incontinence occurs in most cases. If the destruction of the cerebrospinal cord is complete, the toad's limbs can be seen to be flaccid and respiration disappears. Caveat (1) Tissue that has been peeled away from the skin avoids contact with skin venom or other impurities.(2) When separating the nerve, be sure to use a glass split-needle, and do not operate casually with a knife or scissors.(3) The nerve should not be pulled excessively to avoid damage.(4) The specimen should be appropriately moistened with Ren's solution during specimen preparation.(5) Avoid touching or clamping the neuromuscular part of the specimen with fingers or metal instruments. For more product details, please visit Aladdin Scientific website.
1 frog plate, 1 small glass plate 1 pair of coarse scissors, 1 pair of straight scissors 1 pair of large tweezers, 1 pair of small tweezers Ophthalmic scissors Probe Glass minute needle Large beaker Small beaker Dropper Petri dish Cotton wool Ren's solution Zinc-copper fork
Figure 1(2) Clipping the upper limbs and viscera: the spine was cut with coarse scissors 0.5-1.0 cm above the sacroiliac joint. Holding the posterior end of the spine with forceps, all internal organs and cephalothorax were cut along both sides of the spine with scissors, leaving the hind limbs, sacrum, posterior end of the spine and sciatic nerves immediately adjacent to both sides of the spine (Figure 2).
Figure 2(3) Skin peeling: the left hand pinches the broken end of the spine with forceps or directly with the hand (taking care not to compress the nerves), the right hand pinches the skin at the edge of the broken end, and peels off all the skin of the hind limb in a downward direction (Fig. 3), and the specimen is placed in a Petri dish containing Ren's solution. Wash the hands and used instruments before proceeding with the following steps. 
Figure 3(4) Separation of the two legs: the two sciatic nerves are freed along both sides of the spine with a glass split-needle, and a thin wire is tied to each near the spine, then the nerves are cut between the tied wires and the spine. Lifting the thin threads on the nerves, the two sciatic nerves were placed on each thigh, the spine was held in the left hand, the sacrum was cocked, and the inferior spine was cut all the way through. After pinching the iliac bones on each side and separating them in the opposite direction so as to dislocate the pubic symphysis, the two lower limbs were cut along the middle of the pubic symphysis, and one leg was immersed in Ren's solution for spare use, and the other was placed on a glass plate impregnated with Ren's solution.(5) Freeing the sciatic nerve and cutting the femur: identify the sciatic nerve groove and the gastrocnemius muscle, cut the pterygoid muscle and its surrounding connective tissues with scissors, hold the thin wire on the nerve with the left hand, and carefully peel along the sciatic nerve groove with scissors or a glass parting needle with the right hand until the sciatic nerve is peeled to the popliteal fossa. The free and clean sciatic nerve is placed on the lower leg, all the tendons of the thigh are cut along the periphery of the knee joint, and the muscles attached to the lower part of the femur are scraped with scissors, and the upper part of the femur and the attached muscles are cut off at the upper 1/3 of the femur, and the specimen made in this way is known as a sciatic nerve lower leg specimen (Fig. 4). 
Figure 4(6) Freeing the gastrocnemius muscle: On the basis of the lower leg specimen of the sciatic nerve, the lower end of the Achilles tendon is cut with scissors, a thin line is tied at the junction of the Achilles tendon and the muscle, and the line is lifted with the left hand, while the right hand uses scissors to free the gastrocnemius muscle up to the knee joint. Finally, the calf is cut off with thick scissors below the knee joint, leaving what is left is the sciatic gastrocnemius specimen (Fig. 5). The well-made specimen was gently touched to the sciatic nerve with the poles of the zinc-copper fork, if the gastrocnemius muscle contracted immediately, it indicated that the excitability of the specimen was good, then the specimen was put into Ren's solution, and then experiments were carried out after its excitability was stabilized. 
Figure 5