Use of oxytocin to attain cervical dilation for transcervical embryo transfer in sheep

Abstract

Because of the features of the ovine cervix, including a narrow lumen and misaligned folds, access to the uterine lumen through the cervical canal is particularly challenging in this species (Halbert, Dobson, Walton, & Buckrell, 1990). Therefore, surgical procedures are commonly applied in assisted reproductive technologies in sheep when access to the uterine lumen is needed (Candappa & Bartlewski, 2011, 2014). Surgical intervention is not desired in assisted reproductive technologies because it can lead to the formation of adhesions in the reproductive tract (up to 30%) (Bruno-Galarraga et al., 2014; Pinto et al., 2020) and, consequently, reproductive impairment.

Technologies Used in Production Systems for Santa Inês Sheep: A Systematic Review

“…Hormones have also been studied to aid in non-surgical transcervical embryo transfer. For example, a cervical dilation protocol consisting of oxytocin alone ( 51 ) and a hormone combination (estradiol esters, d-cloprostenol, and oxytocin) to induce cervical dilatation before non-surgical retrieval ( 52 ).…”

The use of oxytocin to cause cervical dilation for transcervical insemination in nulliparous goats: Improving pregnancy and kidding rates

“…To improve cervical penetration, in the last 20 years, exogenous dilating hormones have been used to improve the efficacy of AI in adult sheep and goats, as well as to carry out uterine flushing protocols of donor females through non‐surgical methods (Fonseca et al., 2018); for example, the use of oxytocin (Lu et al., 2021; Viudes‐de‐Castro et al., 2009), misoprostol (15‐desoxy‐16‐hydroxy‐16‐methyl PGE1) which is a stable synthetic analogue form of prostaglandin E1 (DeRossi et al., 2009) and dinoprostone (prostaglandin E2 [PGE2]) by means of vaginal devices. Also, local α1 adrenergic blockers (Padilha‐Nakaghi et al., 2020) and the combination of oxytocin and oestradiol (E2) are used both in AI (Jamadi et al., 2017) and in uterine flushing, generally without adversely affecting luteal function (Dias et al., 2020; dos Santos et al., 2020) and lambing rates in ewes (King et al., 2004). However, in vitro studies of bovine luteal cells showed that high concentrations of oxytocin impaired progesterone production whilst low concentrations enhanced it (Tan et al., 1982).…”

Hormonal protocol used for cervical dilation in ewes does not affect morphological embryo quality but reduces recovery rate and temporarily alters gene expression

“…11 These changes induce a reorganization of the collagen fibres of the extracellular matrix by either altering the microstructure of the fibres 12 or stimulating the production of glycosaminoglycans, 13 processes that reduce the muscular tension, relax the smooth muscle, and, consequently, dilates the cervix. 14 Several hormones have been tested with different doses, times, and routes of administration, [15][16][17] but in general, it is assumed that the association of estradiol, oxytocin, and PGF2α provides interesting results. 6,10 These hormones trigger the complex cascade of events that end in cervical dilation, allowing penetration of the cervix and uterine flushing in most ewes.…”