Oviductal insemination by hysteroscopic hydrotubation in mares: a preliminary investigation

Small numbers of sperm were recovered from the oviduct after natural mating or artificial insemination in mares. One advantage of oviductal insemination is that only small number of sperm may be required to achieve pregnancy in a mare compared to numbers required with standard intrauterine insemination. Objective was to investigate the potential for oviductal insemination, using hysteroscopic hydrotubation¹ with small number of sperm. We hypothesized that pregnancy can be established with a small number of sperm, obtained from frozen semen and infused into the oviduct directly through the uterotubal junction by hysteroscopic hydrotubation. Ten mares were used; 5 mares each were assigned into 2 groups and inseminated when preovulatory follicle size reached 35 - 40 mm. Ovulation was confirmed 48 hours after insemination. Progressively motile sperm were selected using the swim-up technique with frozen semen of known fertile stallions (A and B). One straw of 0.5 ml frozen semen was thawed and mixed with 0.5 ml Quinn’s ® Sperm Washing Medium and 1 ml of the same medium was floated onto the mixed solution and incubated for 10 minutes at 37℃. Number of sperm that swam up into the supernatant was counted with a Thoma cytometer. Progressively motile sperm concentrations were 1.3 and 1.2 x 10⁵/ml in the supernatant of Stallions A and B, respectively. In Group 1 (5 mares) frozen semen of Stallion A was used. From 0.1 to 1.0 ml of the supernatant including sperm was mixed with 1.0 or 2.0 ml of the same medium to adjust the number of sperm (1.3, 2.0, 2.0, 4.1, 4.1, and 9.8 x 10⁴) and total volume of medium (1.1, 1.7, 1.7, 1.9, 1.9, and 1.5 ml). Medium, including sperm, was infused into oviduct through uterotubal junction ipsilateral to ovulation site using hysteroscopic hydrotubation. One of 2 mares was pregnant in cases where 2.0 and 4.1 x 10⁴ sperm were used, 1 mare was pregnant with 9.8 x 10⁴ sperm. In Group 2 (5 mares), 1.9 x 10⁴ sperm from Stallion B in 1.7 ml medium was infused into oviducts in 6 cycles of 5 mares by the same procedure used in Group 1. Three of 5 mares (3/6 cycles) in Group 2 were pregnant. In conclusion, oviductal insemination of small number of sperm to achieve pregnancy in mares using hysteroscopic hydrotubation may be a clinically applicable technique.

Keywords: Oviductal insemination, hysteroscopic hydrotubation, mare

Reference

1.Inoue Y: Hysteroscopic hydrotubation of the equine oviduct. Equine vet J 2013;45:761-765

This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.