Impact of equine assisted reproductive technologies (standard embryo transfer or intracytoplasmic sperm injection (ICSI) with in vitro culture and embryo transfer) on placenta and foal morphometry and placental gene expression.

Assisted reproductive technologies (ARTs) such as intracytoplasmic sperm injection (ICSI), in vitro embryo culture and embryo transfer (ET) may be associated with alterations in fetal and placental development. In horses, ET has been used for decades. More recently, in vitro embryo production by ICSI and in vitro culture, followed by embryo transfer (ICSI-C) has become an accepted method for clinical foal production. However, no information is available on the effects of ICSI-C or even of standard ET itself on placental and neonatal parameters in horses. We therefore evaluated placental and neonatal morphology and placental gene expression in reining- and cutting-type American Quarter Horse foals produced using different technologies. Thirty foals and placentas (naturally conceived (NC), ET and ICSI-C; 10 in each group) were examined morphometrically. The only parameter that differed significantly between groups was the length of the foal upper hindlimb, which was longer in ET and ICSI-C than in NC foals. Evaluation of placental mRNA expression for 17 genes related to growth and vascularisation showed no difference in gene expression between groups. These data indicate that within this population, use of ARTs was not associated with meaningful changes in foal or placental morphometry or in expression of the placental genes evaluated.