Effect of cumulus cell removal and sperm pre‐incubation with progesterone on in vitro fertilization of equine gametes in the presence of oviductal fluid or cells

Abstract

In spite of many attempts to establish an in vitro fertilization (IVF) technique in the equine, no efficient conventional IVF technique is available. The presence of oviductal fluid or oviductal cells during IVF help to improve embryo production in vitro but is not sufficient to reach high fertilization rates. Thus, our aim was to perform equine IVF either after sperm preincubation with oviductal fluid or in the presence of oviductal cells, and to evaluate the effect of cumulus removal from the oocyte or sperm preincubation with progesterone. In experiment 1 and 2, IVF was performed in the presence of porcine oviduct epithelial cells. The removal of cumulus cells from equine oocytes after in vitro maturation tended to increase the percentage of fertilization when fresh sperm was used (1/33 vs 4/31, p > 0.05) but had no effect when frozen sperm was used (1/32 vs 1/32). Equine sperm preincubation with progesterone did not significantly influence the fertilization rate when fresh or frozen sperm was used (2/14 vs 2/18 for fresh, 1/29 vs 1/25 for frozen). In experiment 3 and 4, IVF was performed after preincubation of sperm with porcine oviductal fluid. The removal of cumulus cells tented to increase the percentage of fertilization when fresh sperm was used (1/24 vs 3/26, p>0.05). Sperm preincubation with progesterone did not significantly influence the fertilization rate when fresh or frozen sperm was used (2/39 vs 2/36 for fresh, 2/37 vs 1/46 for frozen), but two 3-4 cells stage zygotes were obtained with fresh sperm preincubated with progesterone. This is an encouraging result for the setting up of an efficient IVF procedure in equine.