Figure 1. Summarized representation of different strategies used during in vitro maturation to modulate the intraoocyte concentration of cyclic nucleotides and improve embryo yield in several mammalian species (pigs, cattle, mice, sheep or goat). After each approach, there is a brief schematic description of the methods the authors used. The figure shows the rates of blastocyst in each treatment in comparison to their respective control group. Statistical significance is indicated by the p value. Note that some authors calculate the in vitro performance by dividing the number of blastocyst by the number of oocytes and others by the number of cleaved embryos. IVF: in vitro fertilization; IVC: in vitro culture; PA: parthenogenetic activation.