实验动物 z-bo 2020-08-13 547

　　1. Preparation of sciatic nerve-gastrocnemius specimen of frog or toad

　　1. Experimental principle Some basic life activities and physiological functions of amphibians such as frogs or toads are similar to 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 be maintained for a long time Physiological activity, therefore, frog or toad sciatic nerve gastrocnemius isolated specimens are often used in physiology experiments to observe neuromuscular excitability, excitability process, and skeletal muscle contraction characteristics.

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

　　3. Experimental methods and procedures

　　(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 off the spine with coarse scissors at 0.5-1.0cm on the sacroiliac joint. Clamp the posterior spine with forceps, and 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, posterior spine and the sciatic nerve close to both sides of the spine (Figure 9-34).

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