Effect of Oocyte Recovery Techniques on <i>in Vitro</i> Production of Swine Embryos

Abstract

In vitro production of swine embryos is a valuable tool to generate clones and genetically modified pigs during a short period of time. However, the efficiency of the existing methods is extremely low and the oocyte quality and quantity represent important obstacles on the success of in vitro production of embryos. Therefore, the aim of this study was to compare the in vitro maturation, fertilization and subsequent embryo development rates of oocytes recovered by ovary slicing or follicular aspiration. The oocyte recovery rate (grade 1 COC/ovary) was higher (p = 0.0083) in the slicing group when compared to the aspiration group. No differences were observed between groups regarding in vitro maturation and early cleavage rates. A higher percentage of oocytes recovered by follicular aspiration reached the blastocyst stage after IVF when compared to the ovary slicing method (p = 0.0395). However, no difference on blastocyst cell number was observed. Although the recovery of oocytes using the slicing technique yielded more grade 1 oocytes per ovary than the aspiration method, the number of oocytes that reached the blastocyst stage after IVF by the slicing method was lower when compared with oocytes obtained by aspiration, as observed by lower blastocyst rates. In conclusion, the follicular aspiration is the method of choice for porcine in vitro embryo production.

Identification of optimal assisted aspiration conditions of oocytes for use in porcine in vitro maturation: A re‐evaluation of the relationship between the cumulus oocyte complex and oocyte quality

“…In our investigation of the recovery rates of oocytes, we found that A and B oocytes formed only a minority of the total yield (8.1% and 24.1% of A and B, respectively, Figure 5 ), which is in line with previous findings (Lin et al., 2016 ). Our comparisons of oocytes recovered using different aspiration pressures and needle gauges (Figure 5 , Table 1 ) indicate that both factors affect oocyte recovery; this supports previous work that identified a negative correlation between the size of the COCs retrieved and the aspiration pressure, with higher pressures increasing the incidence of denuded oocytes (Brüssow et al., 1997 ; Marques et al., 2015 ). Furthermore, these data suggest the existence of a compromise between recovery rates and oocyte quality, with quality maximised by lower pressures.…”

“…Aspiration methods can be either manual, using a syringe barrel and needle, or assisted, using a negative pressure aspiration pump and attached needle. Automated aspiration procedures generally allow for a more consistent collection environment when compared to manual aspiration, which is prone to inter‐operator variability (Marques et al., 2015 ). The oocytes retrieved for IVM are found in combination with cumulus cells (CCs), forming the cumulus oocyte complex (COC).…”

“…Due to the many functional roles of CCs, the morphology of the COC is commonly used to determine candidates for IVM in pigs and in other farm animals (Alvarez et al., 2009 ; Nagano et al., 2006 ). Laboratory‐based retrieval methods and aspiration pressures used in ovum pickup from live animals have shown that aspiration pressure also has an impact on the morphology of the COC (Brüssow et al., 1997 ; Marques et al., 2015 ).…”

Investigation of Oocyte Retrieval Methods and Maturation Media on in vitro Development of Porcine Embryos

“…It can then be deduced that the slicing method provides the highest amount of oocytes during collection when compared to aspiration. Marques et al (2015) found similar results, showing that the slicing method produced a higher amount of oocytes than the aspiration method.…”

“…These findings were not in accordance with Lekola (2015) who found no significant differences between the quality of bovine oocytes when using the aspiration or slicing method. Marques et al (2015) found that the aspiration method was the method of choice for later reproductive technologies (p = 0.0395). While they found the slicing method to produce a higher quantity of oocytes, their later study showed that there were no differences between oocyte recovery methods until day 7 post IVF.…”