动物模型,骨神经 z-bo 2020-08-13 544

　　Experimental principle

　　Some basic life activities and physiological functions of amphibians such as frogs or toads are similar to those of warm-blooded animals, and the living conditions of their isolated tissues are easy to master. Under the infiltration of Ren's solution, neuromuscular specimens can maintain physiological activity for a long time, so In physiology experiments, frog or toad sciatic nerve gastrocnemius muscle isolated specimens are often used to observe neuromuscular excitability, excitability process, and skeletal muscle contraction characteristics.

　　1 set of frog surgical instruments and medicines, including: 1 frog board, 1 small glass plate, 1 coarse scissors, 1 straight scissors, 1 large tweezers, 1 small tweezers, 1 ophthalmic scissors, 1 probe, glass 2 minute needles, 1 large beaker, 1 small beaker, 1 dropper, 1 petri dish, cotton thread, Ren's solution, zinc copper fork.

　　1. Destroy the brain and spinal cord: Take a toad and rinse it off with tap water. Hold the toad with your left hand, press the front of the head with your index finger to make the head bend forward, and hold the frog needle from the foramen magnum forward into the cranial cavity with the right hand, stir left and right to destroy the brain tissue, and then withdraw the frog needle to the foramen magnum. After pulling out, the tip is turned and inserted into the spinal canal to destroy the spinal cord. When the spinal canal is inserted, the hind limbs of the toad immediately lose tension, and urinary incontinence occurs in most cases. If the brain and spinal cord are completely destroyed, the toad's limbs are slack and the breathing disappears.

　　2. Cut off the upper limbs and internal organs: Cut the spine at 0.5～1.0cm on the sacroiliac joint with coarse scissors. Clamp the back spine with forceps, use scissors to cut off all the internal organs and the head and chest along both sides of the spine, leaving behind the hind limbs, sacrum, back spine and the sciatic nerve close to both sides of the spine.

　　3. Peeling: Use tweezers or directly pinch the stump of the spine with your left hand (be careful not to compress the nerve), pinch the edge of the stump with your right hand, peel off all the skin of the hind limbs, and place the specimen in a culture filled with Ren's solution In the dish. Wash hands and used instruments before proceeding to the following steps.

　　4. Separate the legs: Use a glass minute needle to free two sciatic nerves along both sides of the spine, and tie a thin thread near the spine, and then cut the nerve between the tie and the spine. Holding the thin thread on the nerve, place the two sciatic nerves on the two thighs, hold the spine in the left hand, tilt the sacrum, and cut off all the lower spine. Pinch the iliac bones on both sides to separate in opposite directions, dislocate the symphysis pubis, cut the two lower limbs along the middle of the symphysis pubis, immerse one leg in Ren's solution for later use, and place the other on a glass plate soaked in Ren's solution on.

　　5. Dissociate the sciatic nerve and cut the femur: recognize the location of the sciatic nerve groove and gastrocnemius muscle, use scissors to cut the piriformis muscle and its surrounding connective tissue, hold the thin thread on the nerve in the left hand, and carefully peel off the sciatic nerve groove with the right hand scissors or glass minute needle , Until the sciatic nerve is stripped to the popliteal fossa. Place the free and clean sciatic nerve on the lower leg, cut all the tendons of the thigh along the knee joint, and scrape the attached muscles of the lower femur with scissors, and cut off the upper femur and attached muscles at the upper 1/3 of the femur. The made is called the lower leg specimen of the sciatic nerve.

　　6. Free gastrocnemius: On the basis of the lower leg specimen of the sciatic nerve, cut the lower end of the Achilles tendon with scissors, tie a thin line at the junction of the Achilles tendon and the muscle, hold the thread with the left hand, and use the scissors to free the gastrocnemius with the right hand until the knee joint. Finally, use coarse scissors to cut off the calf under the knee joint, leaving a specimen of the sciatic nerve and gastrocnemius muscle. The prepared specimen gently touches the sciatic nerve with the poles of the zinc-copper fork. If the gastrocnemius muscle contracts immediately, it indicates that the excitability of the specimen is good. Then put the specimen into Ren's solution and perform the experiment after the excitability is stable.

　　1. The tissues that have been peeled off the skin should avoid contact with skin venom or other impurities.

　　2. When separating nerves, a glass minute needle must be used, and no knife or scissors can be used casually.

　　3. Don't pull the nerve too much to avoid damage.

　　4. During the preparation of the specimen, the specimen should be properly moistened with Ren's solution.

　　5. Avoid touching or holding the neuromuscular part of the specimen with fingers or metal instruments.