Time of ovulation in the brushtail possum (Trichosurus vulpecula) following PMSG/LH induced ovulation

This study aimed to determine the timing of ovulation in response to a new induced ovulation regime for the monovulatory brushtail possum (Trichosurus vulpecula). Ovarian stimulation was achieved by a single subcutaneous inje ction of 15 IU pregnant mare serum gonadotrophin (PMSG). This treatment res ulted in promotion of a large number (9-16) of Graafian follicles >2 mm dia meter on the ovaries. Seventy-two hours later a single intramuscular inject ion of 4 mg porcine luteinizing hormone (LH) was administered to induce ovu lation. Groups of possums were killed 24 hr post-LH injection and subsequen t groups were killed at 6-hr periods up to 48 hr later. Ovulation occurred from 30 hr to 42 hr post-LH. The ovulatory success increased from 3% at 30 hr post-LH to 83% at 48 hr post-LH. Oocytes were recovered primarily from t he oviducts at 36 hr post-LH. Thereafter oocytes were recovered increasingl y from the uteri and by 48 hr post-LH, were only found there. The implicati ons of these observations for artificial breeding in possums are discussed. J. Exp. Zool. 283:608-611, 1999. (C) 1999 Wiley-Liss, Inc.