Sonographic imaging of the glycogen stage of the fetal choroid plexus.

At 8-22 weeks gestation, the lateral ventricular choroid plexus swells with glycogen deposits, which are thought to be an important source of anaerobic energy for a relatively hypovascular stage of brain development. Sonographic images during this phase demonstrate enlarged and echogenic ventricles, accounting for up to 80%-90% of the cerebral axial dimension in the earliest gestations studied. This increased echogenicity may be due to these glycogen stores. Because a rapid but sonographically definable decrease in the relative size of these structures occurs, routine imaging for the presence and character of the choroid plexus might prove to be a useful parameter in fetal examination.