glial chimeras with especially large complements of human astrocytes as well as GPCs. By 7–10 months of age, the majority of all forebrain OPCs and astrocytes in these mice were typically of human origin (Figure 2). The engrafted human glia appeared to mature in a cell-autonomous fashion, in that the diameter, domain size and morphology of human astrocytes in the chimeric mouse brain each approximated that of astrocytes in the normal adult human brain.
