To begin, fix the limbs of the anesthetized animal with tape. Use an electric razor to shave the fur of the lower abdomen and around the urethral meatus. Under the surgical microscope, use Metzenbaum straight blunt scissors to create a one to two centimeter incision in the midline of the abdominal pelvic skin.
Incise the fascia and muscles in the midline to expose the bladder through the incisional wound. Once the bladder is visible through the wound, retract any surrounding organs or tissues, as needed, to obtain a clear view of the surgical field. Then, grasp the bladder dome and use a 5-0 non-absorbable monofilament suture with a taper tip needle to place a purse string.
Using micro scissors, create a small cystostomy within the purse string and make a hole until urine flows out. Now, grasp the round tip end of the catheter and insert it through the hole. Once the tip of the tube has passed through the hole, suture the purse string around the tube.
After that, gently pull the tube outward until the tip is felt under the suture. Then, slowly infuse one milliliter of saline from the other end of the tube to distend the bladder, and check for any leakage around the catheter. Once the saline comes out of the urethra, withdraw the saline to decompress the bladder.
Use surgical scissors to extend the abdominal incision up to the pelvic floor. In line with the bladder, move the muscles and membranes to the pudendal canals and locate the urethra and external sphincter muscle. Using the needle containing the electrode, puncture the skin bilaterally one centimeter away from the urethral meatus.
Then, carefully grab the hook tip with forceps and gently pull the needle away from the skin. Using the electrode's tip, carefully hook the external urethral sphincter muscle bilaterally. Use the 3-0 non-absorbable monofilament to suture the pelvic and abdomen muscles and skin.
To fix the electrodes in place, apply a thin layer of cyanoacrylate glue to the skin where the electrodes exit. Next, use a 0.5 to 10 microliter micro pipette to withdraw the accelerator liquid to dry the glue. Then, add the accelerator liquid to ensure a proper adhesive reaction.
Prepare an inverted polystyrene weighing boat, 4.5 centimeters in length, width and depth. Cut it into a triangle shape with a base of four centimeters to place the mouse's urethral meatus in this space. Put the disposable base mold under the space for collecting the urine.
Then, reposition the mouse in a prone position and carefully move it onto a custom-made plate equipped with a gas mask. Ensure that the urethral meatus is properly positioned within the groove. Gently restrain the head and limbs of the mouse with tape and place the plate on a heating pad until the mouse regains full consciousness.
