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Updated: Aug 23, 2026
A Modified Co-Culture System for Understanding Granulosa-Theca Cell Interactions in the Bovine Ovary
Published on: September 19, 2025
Effects of granulosa coculture on in-vitro oocyte meiotic maturation within a putatively less competent murine model
Boon Chin Heng1, Guo Qing Tong, Soon Chye Ng
1Department of Obstetrics & Gynaecology, Faculty of Medicine, National University of Singapore, 5 Lower Kent Ridge Road, Singapore 119074.
Abstract:
A less competent murine in vitro maturation (IVM) model was achieved by shortening the standard duration of in vivo PMSG stimulation from 48 to 24 h and selecting only naked/partially naked GV oocytes from a mixture of large and small follicles. Porcine granulosa coculture enhanced meiotic maturation within such a less competent model (37.3% versus 23.1%, P<0.05), while no significant enhancement was observed with macaque and murine granulosa coculture. Culture of porcine granulosa on extracellular matrix (ECM) gel resulted in a more differentiated morphology, but did not significantly further enhance the beneficial effects it already had on meiotic maturation. Increased concentrations of serum as well as the supplementation of gonadotrophins and follicular fluid within the culture milieu did not enhance IVM under both cell-free and coculture conditions. Porcine granulosa-conditioned medium also enhanced meiotic maturation (36.5% versus 26.7%, P<0.05), which was not diminished upon freeze-thawing (35.8% versus 22.6%, P<0.05). Enhancement of meiotic maturation by porcine granulosa coculture did not however translate to significant improvements in developmental competence, as assessed by in vitro fertilization (IVF) and embryo culture to the blastocyst stage, followed by total cell counts. ECM gel had a detrimental effect on fertilization and developmental competence, even though it had no detrimental effect on meiotic maturation itself.
Insights
Porcine granulosa coculture significantly improved in vitro maturation (IVM) in a less competent mouse model. However, this enhancement did not improve subsequent embryo development after in vitro fertilization (IVF).
Area of Science:
- Reproductive Biology
- Oocyte Maturation
- In Vitro Gamete Technology
Background:
- Developing robust in vitro maturation (IVM) models is crucial for assisted reproductive technologies.
- Standard IVM protocols often face challenges with oocyte competence and developmental potential.
- Investigating supportive cell types and culture conditions can optimize IVM outcomes.
Purpose of the Study:
- To establish a less competent murine in vitro maturation (IVM) model.
- To evaluate the efficacy of porcine granulosa cell coculture in enhancing IVM.
- To assess the impact of extracellular matrix (ECM) gel and conditioned media on oocyte maturation and developmental competence.
Main Methods:
- A reduced IVM model was created by shortening PMSG stimulation and selecting specific oocytes.
- Coculture with porcine, macaque, and murine granulosa cells was performed.
- Porcine granulosa cells were cultured on ECM gel; conditioned media was also tested.
- IVM rates were assessed, followed by in vitro fertilization (IVF) and embryo culture to blastocyst stage.
Main Results:
- Porcine granulosa coculture significantly enhanced meiotic maturation (37.3% vs 23.1%) in the compromised IVM model.
- Porcine granulosa-conditioned medium also improved maturation rates, even after freeze-thawing.
- Neither ECM gel culture nor supplementation with serum, gonadotrophins, or follicular fluid improved IVM.
- Enhanced meiotic maturation did not translate to improved fertilization or blastocyst development rates.
- ECM gel negatively impacted fertilization and developmental competence.
Conclusions:
- Porcine granulosa coculture and conditioned medium can enhance meiotic maturation in a suboptimal murine IVM system.
- The benefits of porcine granulosa support on maturation do not extend to improved developmental competence post-IVF.
- Extracellular matrix gel is detrimental to fertilization and embryo development, despite not affecting initial meiotic maturation.
