Table III.

Current gaps and opportunities in follicle and oocyte in vitro culture.

Component	Controversy
Follicle harvest strategy	Isolated follicle culture versus in-situ or in ovo culture systems
Follicle attachment system	Use of adherent versus non-adherent culture systems
Follicle growth strategy	Use of linear (2D) versus spherical (3D) culture systems
Culture matrix	Inclusion versus exclusion of matrix and/or scaffolds to support 3D culture and antrum formation
Culture system continuity	Use of consistent system for all stages of follicle growth development versus sequential, follicle phase-dependent systems
Base media	Optimization of base media and buffering systems to suit species and culture strategy
Oxygen tension	Use of high (20%) versus low (5–6%) oxygen tensions
Media supplementation	Use of serum-based versus defined serum-free media
Developmental timeframes	Use of accelerated versus protracted growth systems
Growth additives	Supplementation of media with pharmacological versus physiological doses of growth additives
Hormonal additives	Supplementation of growth media with FSH and/or LH and estrogen and/or androgens
Metabolic requirements	Use of continuous versus sequential systems that modify the culture environment to meet the changing metabolic requirements of follicles and oocytes during in vitro growth and maturation
Culture starting and end points	Optimal initial and terminal size for oocytes and follicles at the start and end of follicle culture, species dependent
End-point measures	Agreement on best end-point measures, including morphology, viability assays, follicle and oocyte dimensions, growth rates, hormone secretion, cell signalling, molecular markers, IVM, fertilization, embryo production and live births
Normality testing	Agreement on how and what markers to measure to definitively test the normality, methylation and epigenetic programming, fertility and developmental competence of in vitro cultured oocytes and the embryos they produce