Abstract
Brilliant cresyl blue (BCB) staining is used to select developmentally competent cumulus-oocyte complexes (COCs) for in vitro maturation (IVM). However, limited attention has been paid to what drives the higher developmental competence of BCB+ COCs. Sonic hedgehog signaling (SHH) is an important signaling pathway for ovarian follicular development and oocyte maturation. Therefore, this study investigated the effect of oocyte quality assessed by BCB staining on cumulus cell expansion, oocyte nuclear maturation, subsequent embryo development, apoptosis levels, and SHH signaling protein expression, in porcine COCs. After IVM, BCB+ COCs exhibited a significantly higher proportion of complete cumulus cell expansion and metaphase II rate in oocytes than BCB- COCs. After in vitro fertilization, the BCB+ group showed a significantly higher monospermy rate, fertilization efficiency, percentage of cleavage and blastocyst formation, with a higher total cell number and a lower apoptosis in blastocysts as compared with the BCB- group. Furthermore, significantly lower apoptosis levels and a higher expression of SHH-signaling proteins in COCs were observed, before and after IVM. In conclusion, high-quality oocytes had a greater potential to expand their surrounding cumulus cells with active SHH signaling and a lower apoptosis. This could provide COCs with a proper environment for maturation, thereby leading to a better subsequent embryo development.
Highlights
The in vitro maturation (IVM) of immature oocytes is an important assisted reproductive technology (ART) capable of generating mature oocytes that can develop to term [1]
It has been suggested that higher rates of subsequent embryo development of oocytes can be attributed to cumulus cell expansion [10], and the relationship between cumulus cell expansion and the quality of oocytes could be regulated by Sonic hedgehog (SHH) signaling [11,12]
We investigated the cumulus cell expansion, nuclear maturation of oocytes, subsequent development of parthenogenetic activation (PA) and in vitro fertilization (IVF) embryos, apoptosis levels, and SHH signaling in cumulus-oocyte complexes (COCs) between Brilliant cresyl blue (BCB)- and BCB+ porcine COCs
Summary
The in vitro maturation (IVM) of immature oocytes is an important assisted reproductive technology (ART) capable of generating mature oocytes that can develop to term [1]. When the SHH ligand binds to the Patched (PTCH1) receptor on the cell surface, its inhibitory action on Smoothened (SMO), the seven-transmembrane G-protein-coupled coreceptor, is relieved This allows SMO to activate the glioma-associated oncogene homolog 1 (GLI1) transcription factor, resulting in an upregulation of the target genes, which control cell patterning, proliferation, and differentiation during development [21]. These elements (PTCH1, SMO, and GLI1) of active SHH signaling were found in the granulosa and cumulus cell layer of oocytes, and supplementation with SHH protein during the IVM of oocytes was demonstrated to promote oocyte maturation and subsequent embryo development [22]. We investigated the cumulus cell expansion, nuclear maturation of oocytes, subsequent development of parthenogenetic activation (PA) and in vitro fertilization (IVF) embryos, apoptosis levels, and SHH signaling in COCs between BCB- and BCB+ porcine COCs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
