Amphibian oocytes are used for studies in molecular biology, embryology and biochemistry. Stage I-VI oocytes are obtained by surgical laparotomy. Multiple surgeries on a single animal may be justified for oocyte collection considering the reduction in the total number of animals used over the long-term. However, the total number of animals used must be considered relative to the pain or distress experienced by an individual animal.

  1. The total number of laparotomies shall be limited and will depend on the condition of the animal and quality of the oocytes as well as the life span of the animal and the duration of egg production. Up to five recovery surgeries (the 6th would be terminal) per animal are acceptable. Additional survival surgeries require approval by the ARC.
  2. Surgeries shall be performed by trained personnel using appropriate anesthesia such as tricaine methane sulfonate (MS-222). Cryoanesthesia is not considered an acceptable method.
  3. Aseptic technique is required to minimize adverse effects of microbial contamination on oocyte quality and general frog health. Aseptic technique includes proper surgical site preparation and the use of sterile gloves, sterile drapes, and sterile instruments. Povidone-iodine solution (10%) has been found to yield effective surgical site preparation with no observed skin irritation or other deleterious effects.
  4. A sharp incision, less than 1.5 cm in length, should be used. Surgical sites should be alternated between left and right ovaries.
  5. Incisions shall be closed using a continuous pattern, which is more likely to seal the wound and prevent entry of water. A two-layer closure (body wall and skin) should be performed using a non-capillary suture (e.g., nylon or polypropylene).
  6. Frogs shall be returned to a clean tank following surgery. Single housing or small group housing for several days after surgery should be considered as part of the post-surgical care of laparotomized animals. Frogs should be monitored daily during this period for appetite as well as for any complications, such as infection or rupture of the surgical site (dehiscence). Such adverse effects would be reasons for immediate euthanasia.
  7. Adequate recovery time shall be allowed between laparotomies. The investigator should consider rotation of frogs so that the interval between surgeries in any individual animal is maximized. Recovery time of less than one month requires approval by the ARC.
  8. Contact the Division of Laboratory Animal Medicine (DLAM) if animal death or illness occurs after a surgical procedure. A member of the veterinary staff can help evaluate the cause and outline a solution.


References

  1. Elsner, H.A., Honck, H.H., Willman, F., Kreienkam, H.J., Iglauer, F.  2000. Poor Quality of Oocytes from Xenopus laevis Used in Laboratory Experiments: Prevention by Use of Antiseptic Surgical Technique and Antibiotic Supplementation. Comp. Med. 50(2):206-211.
  2. Green, S.L.  2002. Factors Affecting Oogenesis in the South African Clawed Frog (Xenopus laevis). Comp. Med. 52(4):307-312.


Approved 11/26/01; Revised 6/9/03