ICSI – A biotechnological method to produce equine embryos in vitro

Development of assisted reproductive technologies in horses has been slow compared to other domestic animals, like ruminants and pigs. Not only the scarce availability of oocyte, but also the lacks of interest from horse breeders have been the main reason for this delay. In the last few years there has been increasing interest in obtaining foals via assisted reproduction from mares. Efficient methods for oocyte recovery from live mares have generated clinical interest in methods for in vitro fertilization (IVF). The conventional method of IVF (maturation of oocytes, culture of oocytes with capacitated sperm, cultivation of zygotes), as used in the bovine, has proved to be inefficient in the horse (Alm et al. 2001). Therefore, a method for more efficient production of equine embryos has been developed – the intracytoplasmic sperm injection (ICSI). With ICSI, one spermatozoon is injected into a mature oocyte. Equine embryos produced by in vitro maturation, ICSI, in vitro embryo culture and transferred transcervically to recipient mares have resulted in the birth of normal foals. Fertilized equine oocytes, produced by ICSI, are also being used to develop effective equine embryo culture systems.