179 AUTOGENOUS TRANSFERS OF INTRACYTOPLASMIC SPERM INJECTION-PRODUCED EQUINE EMBRYOS INTO OOCYTE DONORS’ UTERI

Intracytoplasmic sperm injection (ICSI) is used to produce offspring from stallions with poor quality or limited availability of semen. Embryos produced by ICSI can be cultured to a stage of development suitable for nonsurgical transfer into recipient uteri. However, use of a recipient is expensive, and transfer of an ICSI-produced embryo back into the oocyte donor's uterus would allow her to carry the pregnancy. We attempted autogenous transfers of ICSI-produced embryos back into the oocyte donors’ uteri for 3 mares in a clinical setting. Three Quarter Horse mares, aged 9, 10, and 13 years, were admitted to the clinical assisted reproduction program at Colorado State University's Equine Reproduction Laboratory (Fort Collins, CO, USA). When a follicle or follicles at least 33 mm in diameter, relaxed cervix, and uterine oedema were observed, deslorelin acetate (1.25 mg, IM) and hCG (2000 IU, IV) were administered. Approximately 22 h later, oocytes were collected by transvaginal, ultrasound-guided follicular aspirations. Oocytes were placed in culture, and 18 to 20 h later, ICSI was performed using frozen sperm from 4 stallions (A–D), all with limited semen availability. Resulting embryos were cultured in DMEM/F12 with 10% fetal calf serum at 38 to 38.5°C for 5 or 6 days, when all embryos reached the blastocyst stage. Oocyte and embryo cultures were performed as previously described (Carnevale et al. 2010 Anim. Reprod. Sci. 121S, S241–243). Blastocysts were transferred nonsurgically into the uteri of recipients or donors, and pregnancies were observed by ultrasound at 12, 16, 25, and 35 days. The 9-year-old donor had 2 oocyte collection cycles. An oocyte was not retrieved during the first cycle; 2 oocytes were collected the second cycle, resulting in 2 blastocysts. One blastocyst was transferred into a synchronized recipient, who did not become pregnant; the second blastocyst was transferred into the donor, resulting in a pregnancy (stallion A). The 10-year-old mare had a single oocyte collection cycle yielding 2 oocytes, and 2 blastocysts were produced from the same stallion (B). One blastocyst was transferred into the uterus of a synchronized recipient, and one blastocyst was transferred back into the donor's uterus. Both mares were diagnosed pregnant, but the recipient lost the pregnancy between 25 and 36 days. The 13-year-old donor donated a single oocyte during her first cycle, resulting in a blastocyst that was transferred into a recipient and a pregnancy (C). Two oocytes were obtained during the subsequent cycle and injected with sperm from different stallions; 1 presumptive zygote did not cleave after ICSI (D), and the second resulted in a blastocyst that was transferred back into the donor, resulting in a pregnancy (A). In total, 7 oocytes were collected during 5 cycles, resulting in 6 blastocysts and 5 pregnancies, with ongoing pregnancies in 1 recipient and in the 3 oocyte donors. Pregnancies were established for 3 stallions (A–C). The methods used were effective in producing clinical pregnancies in oocyte donors after oocyte collection, ICSI, and nonsurgical embryo transfer.