Fig. 1.

Distinct classes of astrocytes in the human brain. a Location of the four distinct types of human astrocytes within different layers of the cortex. Scale bar 100 µm. b Interlaminar astrocytes in the human occipital cerebral cortex. The dashed line indicates the limit of layer I. Scale bar 100 µm. c Graphical representation of mouse (top) and human (bottom) cortical protoplasmic astrocytes, showing that human astrocytes are almost threefold larger and more symmetrical than mouse astrocytes. Scale bar 25 µm. d Representative human protoplasmic astrocyte diolistically labelled. Inset colocalization with GFAP (green). Scale bars 20 µm. e Representative varicose projection astrocyte (left) and enlarged view of the area indicated by the yellow box, which highlights the varicosities along the processes. Scale bars left, 20 µm; right, 10 µm. f Representative human fibrous astrocyte. Scale bar 20 µm. [a, c adapted from (Oberheim et al. 2006); b from (Colombo and Reisin 2004); d–f adapted from (Oberheim et al. 2009)]