Fig. 4: Population of Piwi/Dpn-expressing cells in the cortex glia of the adult brain expands during aging.

a Left panel, an optical section of the whole brain showing symmetrically located Piwi-expressing cells (arrows). Frequently, Piwi-positive cells are heterogeneous in size and Piwi-expression levels and clustered together in each half of the brain (middle panel). Piwi is exclusively cytoplasmic (right panel). b Co-staining of brains with anti-Piwi (green channel) and anti-Dpn (magenta) antibodies shows colocalization of both proteins in the cells. The images are optical sections obtained with the super-resolution confocal microscopy. The top panels for each channel were generated from six tiles, individually imaged with super-resolution microscopy, to show all cells in a single brain. The bottom panels show super-resolution microscopy images of Piwi and Dpn colocalizing in a single cell. c, d Piwi (c) and Dpn (d)-positive cells (magenta) are enveloped by cortex glia labeled with membrane marker GFP-mCD8 (green). e The number of Piwi-(green) and Dpn-(magenta)-expressing cells (indicated with arrows) is increased in aging brains (overlay images of brains at a specified age are shown). f Percentage of brains with Piwi/Dpn-positive cells with two or less cells (green bars) and more than two cells (magenta bars) are shown for four different ages. Number of brains counted for each age is indicated above the bars. Scale bar in a (left panel) is 50 μm, a (middle panel) 10 μm, a (right panel) 5 μm, b (top panels) 20 μm, b (bottom panels) 2 μm, c and d 5 μm, and e 50 μm.