This article describes the procedure for embryo transfer in rabbits, focusing on the steps necessary to ensure successful implantation. The process involves inducing pseudopregnancy, surgical techniques, and careful monitoring of the recipient rabbit.
To perform embryo transfer, take an unfertilized rabbit doe. Inject the rabbit intramuscularly with a synthetic analog of the gonadotropin-releasing hormone. This procedure induces ovulation and allows the rabbit to exhibit pseudopregnancy - a condition where the body exhibits pregnancy-like symptoms without having a viable fetus, which increases the chances of embryo survival in the subsequent steps.
Anesthetize the rabbit and place it supine, in an inclined position with the feet elevated above its head. This position shifts abdominal organs upward, ensuring enough gap from the reproductive organs. Make an opening in the anterior portion of the abdominal region. Use this area to insert an endoscopic camera inside the peritoneal cavity to visualize the reproductive system.
Now, take a syringe-catheter assembly containing viable embryos. Insert the needle near the oviduct – a canal that passes the embryo toward the uterus. Advance the catheter through the end of the funnel-shaped cavity or infundibulum till it reaches the ampulla – a long tubular position of the oviduct.
Release the embryos into the ampulla. Retract the catheter and remove the camera. Seal the incision site. Transfer the rabbit to its cage and monitor it. The embryos migrate from the ampullary region toward the uterine horn – the part of the uterus where implantation occurs. Healthy embryos get implanted, eventually leading to a successful pregnancy.
On the day of the transfer, rinse the fresh or thawed embryos in 37 degrees Celsius base medium under a stereo microscope, and attach an appropriately configured 17 gauge epidural catheter to a 1-milliliter syringe. Aspirate one centimeter of base medium into the catheter followed by a small air bubble. Then, aspirate 5 to 7 embryos and 10 microliters of base medium, followed by another small air bubble in a final one centimeter of base medium.
Once the embryos have been loaded, place an anesthetized recipient rabbit in a cage on a warming stage, and apply ointment to the animal's eyes. After confirming a lack of response to pedal reflex, shave the fur from the ventral abdomen, clean the surgical area with chlorhexidine gluconate soap, and remove any remaining hair.
Cover the area with a sterile drape with a hole for the surgical area, and insert one endoscopic trocar 5 centimeters into the abdominal cavity, 2 centimeters caudal to the xiphoid process, and use a pressure-regulating mechanical insufflator to inflate the peritoneal cavity.
Insert the endoscope camera through the endoscopic trocar, and insert the 17-gauge epidural needle into the inguinal region 2 to 3 centimeters from the infundibulum. Insert the loaded catheter through the epidural needle into the abdomen, and insert 1 to 2 centimeters of the epidural catheter through the infundibulum in the ampulla.
Gently depress the catheter plunger to release the embryos into the oviduct. Both air bubbles must exit from the catheter. Remove the catheter just after the embryos have been released, and aspirate and release the remaining medium to confirm the absence of the embryos.
After confirming a successful transfer of the embryos, remove the epidural needle and the endoscope camera, and release the abdominal carbon dioxide through the endoscopic trocar. Clean the trocar incision with chlorhexidine solution, and close the wound with a micronized aluminum and a plastic dressing. Then, treat the animal with the appropriate antibiotics and analgesics and monitor the animal until full recovery.
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