Cells immunoreactive for S100B and vimentin in the fusiform gyrus and inferior temporal gyrus of DS and euploid fetuses. A. Examples of S100B‐positive cells (indicated by red arrows) in the fusiform gyrus of a euploid and a DS fetus of the same gestational age (GW21). Calibration = 20 µm. B,C. Density (left panel) and percentage (right panel) of S100B‐positive cells in the cortical plate of the fusiform gyrus (B) and inferior temporal gyrus (C) and of vimentin‐ positive cells in the cortical plate of the fusiform gyrus (D) and inferior temporal gyrus (E) of DS (n 54; GW18, GW19, GW20, GW21) and euploid (n 5 4; GW17, GW19, GW20, GW21) fetuses. Values are mean 6 SD. The number in parentheses indicates the number of samples analyzed for each experimental group. * P < 0.05; ** P < 0.01 (two tailed t‐test). Abbreviations: EU, euploid; DS, Down syndrome; GW, gestational week.