In the present small experimental series of litters, the following additional variables did not have significant effects: number of viable embryos in the litter, position in the uterus, or the size or Igf2 status of nearest neighbors. In each recombination series, the comparisons were between manipulated normal conceptuses (normal ICM + normal trophectoderm) and manipulated experimental combinations in the same litters (e.g., ICM Igf2 ko + normal trophectoderm). buy ventolin inhalers
When no IGF-2 was expressed in the derivatives of either the trophectoderm or the ICM, then the placenta + fetus had 68% normal wet weight at E16.5, confirming the original description of the phenotype (Table 1, ). When only one of these components lacked IGF-2 production, then growth retardation was less (Table 4). This partial alleviation of the syndrome could be due to either systemic endocrine effects of IGF-2 produced in one part, or to the near-normal size of one part providing additional trophic functions for the other. It is clear that neither derivative has absolute control over the growth of the other because the main wet weight deficiencies are localized to the sites of IGF-2 loss (Table 4).