• ICSI is the injection of a single sperm into a mature oocyte (eggs) in the laboratory using micromanipulation techniques.
• Invitro fertilization (IVF) is successful in other species but not the horse.

• ICSI provides a means of overcoming the problems of IVF in horses.
• Clinical use of this technology provides a means of producing foals from sub fertile mares and stallions and assists in rescuing the fertility of aged mares and stallions.
• ICSI employs ovum pick up (OPU) of mature oocytes (eggs) from the donor mares by follicle aspiration.
• OPU can also harvest immature oocytes and those eggs can be cultured in the lab until they become mature oocytes (metaphase ll).
• The mature oocytes are then injected with a single sperm cell using micromanipulation techniques.
• The resulting fertilized egg is cultured in the lab until it reaches the expanded blastocyst stage (day 6,7,8, or 9)
• The embryo can then be transferred non-surgically to a recipient mare (preferably 5 days post ovulation) or frozen for use later.

RESULTS A group in Italy (Silvia Colleoni,PhD;Sandro Barbacini,DVM*,etal) has reported the following results:

808 follicles were aspirated and 404 oocytes recovered
66% (266) of these were mature (metaphase ll) and were fertilized by ICSI
40 blastocysts were obtained after culture in the lab, of which 18 were non-surgically transferred into recipient mares.
Of the 18 transfers 15 resulted in pregnancy
5 of these pregnancies were lost before 60 days.
A group at Colorado State University (Elaine M.Carnevale,DVM,MS,PhD;JoAnne Stokes,BS;
Edward L.Squires,PhD,Diplomate ACT etal) has reported the following results:

• From 91 normal oocytes, after ICSI, 62 (68%)cleaved into at least two cells.
• Embryos were surgically transferred into the oviducts of recipient mares 34 hr after ICSI
• After 60 days of gestation, 31% remained pregnant.

CONCLUSIONS

• The loss of fertility associated with aged oocytes can be overcome with ICSI
• Poor semen quality does not affect the production of embryos using this technique
• There is no effect of season on the production of embryos using this technology
• The techniques of oocyte harvesting (OPU) and blastocyst production appear safe.