Polyacrylamide gel as a culture substrate improves in vitro oocyte growth from porcine early antral follicles.

A major difference between in vivo and in vitro follicle culture is the stiffness of the substrate in which the follicles grow. In this study, we examined the effect of polyacrylamide gel (PAG), as a culture substrate, on the development of porcine oocytes derived from early antral follicles. Oocyte-granulosa cell complexes (OGCs) were collected from the early antral follicles of gilts, and incubated individually for 14 days in a 96-well culture plate without or with PAG. We then evaluated the number of granulosa cells present in OGCs as well as the abundance of ATP, lipid, and acetylated lysine in oocytes. OGCs cultured on PAG showed significantly greater antrum formation and granulosa cell proliferation than controls cultured on standard plastic. Oocytes grown on PAG also possessed significantly larger diameter, ATP and lipid content, and lysine acetylation, as well as competence to develop to the blastocyst stage. Transcriptome analysis of the granulosa cells revealed that genes involved in follicular development and mechanosensing are up-regulated under PAG culturing conditions. Thus, in vitro culturing OGCs on PAG profoundly induced granulosa cell proliferation, resulting in improved developmental competence of the oocytes. Mol. Reprod. Dev. 84: 44-54, 2017.