This image shows a coronal magnetic resonance image of a pregnant rhesus macaque on the 110th day of a 168 day gestational term. This view provides a sagittal image of the fetus. Overlaid is a lateral view of a surface model of the cerebral cortex, color-coded according to fractional anisotropy (FA) of cerebral cortical water diffusion measured in utero. Orange colors indicate low FA and yellow colors indicate high FA. Wang and co-workers demonstrate how temporal and regional changes in FA relate to morphological development of cells within the cerebral cortex, and in turn, how these changes relate to macroscopic folding and surface area expansion of the fetal primate brain. For more information, see the article by Wang et al. (pages 1971–1983).