Surgical oocyte retrieval (SOR): a method for collecting mature mouse oocytes without euthanasia

A novel surgical method for collecting oocytes from unique and irreplaceable mice is described. This method, surgical oocyte retrieval (SOR), facilitates the collection of ovulated oocytes, does not require euthanasia, and preserves reproductive potential. The surgery involves a small incision in the ampulla region of the oviduct, through which the cumulus oocyte mass is removed with a gel-loading pipette. The incision then is closed by using a tissue adhesive, which is required to ensure healing of the incision and containment of any oocytes ovulated after SOR. Two anesthetics, isoflurane and tribromoethanol, were compared for oocyte toxicity during SOR. More dead oocytes were recovered when tribromoethanol was used than when isoflurane was used. Combining SOR and traditional oocyte collection methods yielded more oocytes per BALB/cByJ than did traditional methods alone (41 versus 28 oocytes, respectively). Oocytes collected by using SOR were fertilized and subsequent embryos developed to term comparable to controls. This technique provides an alternative method for oocyte collection and will be valuable for maximizing the number of oocytes from irreplaceable mice.