ABSTRACT
Most of the culture media used in human in vitro fertilization (IVF) were first developed for laboratory rodents and domestic species and modified for use in humans. The difficulty in obtaining human eggs and embryos for research has resulted in limited information regarding their metabolic requirements in culture, and although significant advances have been made, deficiencies still exist in providing suitable media for human IVF and embryo culture. Culture media for human IVF are usually supplemented with protein; it is unlikely, however, that protein is required for early embryo development. The type of protein used to supplement culture media varies widely. Maternal and fetal cord serums were the first protein supplements used for IVF, and maternal serum is commonly used. Coculture enhances human embryo quality, improves embryos' development in vitro, and improves pregnancy rates after IVF. Fertilization and early embryo development occur in the fallopian tube, and culture systems for IVF have attempted to mimic the environment.
