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. Issue 2 (21st November 2020)

• Record Type: Journal Article
• Authors: Silvestri, Giuseppe; Rathje, Claudia C.; Harvey, Simon C.; Gould, Rebecca L.; Walling, Grant A.; Ellis, Peter J.I.; Harvey, Katie E.; Griffin, Darren K.
• Is Part Of: Veterinary medicine and science. Volume 7:Issue 2(2021)
• Page Start: 465
• Page End: 473
• Publication Date: 2020-11-21
• Subjects: In vitro production -- Morphology -- Oocyte -- Pig; Veterinary medicine -- Periodicals; Animal Diseases; Veterinary medicine; Periodicals; Periodicals; 636.08905
• DOI: 10.1002/vms3.378
• Languages: English
• ISSNs: 2053-1095

Abstract

Abstract: The quality of porcine oocytes for use in IVF is commonly graded according to the number of layers of cumulus cells (CCs) surrounding the oocyte; together these form the cumulus oocyte complex (COC). At least three compact layers of CCs is regarded as important for efficient IVP. To test this, oocytes were scored according to cumulus investment, with grade A representing COCs with three or more cumulus layers including granulosa cell‐cumulus oocyte complexes, grade B those with an intact corona radiata surrounded by another layer of cumulus cells and grades C and D representing COCs with lower CC investment. These oocytes were then monitored for in vitro maturation (IVM), as assessed by tubulin immunostaining for meiotic progression, the development of a cortical granule ring, and by glutathione levels. Results indicate that grading correlates closely with nuclear maturation and cytoplasmic maturation, suggesting that grading oocytes by cumulus investment is a reliable method to predict IVM success. Importantly, Grade A and B oocytes showed no significant differences in any measure and hence using a cut‐off of two or more CC layers may be optimal. We also determined the effect of assisted aspiration for oocyte retrieval, comparing the effect of needle size and applied pressure on the retrieval rate. These data indicated that both variables affected oocyte recovery rates and the quality of recovered oocytes. In combination, these experiments indicate that grade A and B oocytes have a similar developmental potential and that the recovery of oocytes of these grades is maximised by use of an 18‐gauge needle and 50 mmHg aspiration pressure. Abstract : The global population is expected to rise dramatically over the next few decades. This means that the demand for meat, including pig derived products will also increase, and that a more sustainable way to produce such products is necessary. The establishment of production scale pig embryo in vitro production (IVP) could be one answer to this problem, however some challenges still exist, one of which is that pig IVP requires the consistent isolation of large numbers of high‐quality oocytes. Here, ways of maximising both the yield and the developmental potential of oocytes from abattoir derived ovaries has been investigated.