Fig. 7. Model for Fpn1-mediated embryonic iron deficiency and spleen stromal defects in Pcm mice. Decreased Fpn1 mRNA and protein expression in placental syncytiotrophoblast cells leads to decreased maternal-to-fetal iron transport and embryonic iron deficiency. Although the spleen exhibits decreased Fpn1 mRNA, increased Fpn1 protein is observed, which should mediate cellular iron efflux from stromal cells. Under the influence of iron deficiency and/or hypoxia, spleen stromal cell death translates to decreased organ size and defects of the red pulp vascular endothelium. The broken line indicates the uncertain relationship between decreased Fpn1 expression in the fetal liver and the functional consequences, for instance with regard to fetal erythropoiesis.