1. Fixation: The mouse must be fixed, and the tail cannot move during injection. I have been using a mouse retainer to fix it, and another person gently clamped the base of the tail with his fingers, which generally held it well. (I am looking for a 500 or 1000ml beaker and stuck it upside down on the table, and the mouse can be placed inside to expose its tail)
2. For the choice of blood vessels, generally speaking, there are three veins in the tail of mice, one on each side and it is relatively shallow, easy to puncture; the middle one is deeper, not easy to penetrate, it is recommended not to choose as much as possible. In addition, puncture It is better to choose 2/3~1/2 in the middle and lower part of the tail, because the skin is thin here, my experience is that 75% alcohol can be used to repeatedly wipe the puncture blood vessel to fill it and soften the cuticle of the skin, which is good for puncture Or before the injection, the tail of the mouse is soaked in warm water (about 50 degrees) for about 2 minutes, so that the blood vessels can fully relax. Wipe dry with a dry cotton ball.
The blood vessels should be selected from the two sides of the blood vessels, from the bottom up. The advantage of this is that you can continue to use this blood vessel in case you can't penetrate it once.
3. Needle choice: The book says to use a 1ml syringe. Some people use a scalp needle in practice, followed by a 1ml syringe. Because the scalp needle has a smaller needle and less damage to blood vessels, it is suitable for multiple continuous injections. After puncturing with a scalp needle, we can judge whether the puncture is successful by returning blood. (My experience is that the 4 and a half 1 ml syringe is sufficient and easy to insert)
4. Injection technique:
Use your left index finger and middle finger to pinch the side of the blood vessel you selected on the side close to the body. The ring finger and little finger are placed on a piece of gauze or paper towel (to establish a puncture plane), and the thumb presses the tail tip of the selected blood vessel and clamps the blood vessel up and down. The distance should be so that it does not affect the movement of the needle in the right hand. (Otherwise, it is easy to artificially establish the puncture angle, and the puncture needle in the right hand will be punctured too deeply, which will cause the puncture to fail.) The needle can be inserted flat, and the blood return indicates success, and it can also be drawn back.After seeing the blood return, it indicates that the puncture has entered the blood vessel and can be administered.
Straighten the tail of the mouse with your left hand, hold the middle and lower 1/3 of the 1ml syringe with your right hand, and insert the needle at the lower 1/3-1/2 of the tail at an angle (about 10 degrees). , After inserting the needle, lift the needle up slightly, and then move the needle inward a little. If it is in the blood vessel, there is no resistance and the needle can be seen. If the needle can be seen clearly, it has been pierced under the skin; if the needle cannot be seen clearly, it has been pierced deeply. Liquid verification can be pushed gently. (After contacting so many times, I found that the needle could not be inserted smoothly at the beginning, most of the reason was that it was inserted and then there was a process of provoking)
5. After the puncture, use gauze to press the reflexed tail of the puncture site to stop bleeding. A good and thorough hemostasis can protect the blood vessels, which is very useful for puncturing and drug delivery every day. (General mice It takes a long time to press, otherwise it will easily cause bleeding)