[Growth factors: from oocyte maturation to blastocyst]

Developmental arrests and losses of viability are observed in vitro, when embryos are cultured. A harmonious oocyte maturation is essential to obtain a balanced development. Factors that control this maturation are still unknown but growth factors seem to be involved: they are present in ovary and some of them (EGF, TGF-alpha, TGF-beta, PDGF) improve in vitro maturation. These factors are also involved in preimplantation development, either in an autocrine way (ligand and receptor genes expression in the embryo) or in a paracrine way (receptor gene expression in the embryo and ligand gene expression in the tractus). However, the precise role of each one and their interrelations are still speculative.