Growth factors and embryo development

In this review are cited and discussed the possible roles of growth factors on preimplantation embryo development of different species. In first term, is considered the mRNA detection in early stages of development. The distr ibution pattern was not uniform for the different peptides evaluated. For s ome of them, the mRNAs are detected at the oocyte stage and the level decli nes to the blastocyst stage, which suggests a maternal origin for them. For others, the level increased from 2-4 cells to blastocyst stage. On the oth er hand, transcripts of growth factor receptors have been detected in preim plantation embryos. This suggests that growth factors of maternal or embryo origin interact with specific receptors on preimplantation embryo surface and regulate the early development. On the other hand, culture media supple mented with different growth factors have been used to study the possible e ffects on in vitro development. Some investigators have found no effect. Ot hers, however, have demonstrated changes in protein synthesis, cell number, differentiation and hatching processes. Embryo development modulation by g rowth factors probably involves a balance between stimulatory and inhibitor y effects, although works are needed to determine the precise roles played by these polypeptides during early stages of mammalian development.