A. Neurons in fixed coronal slices from 1-month (top) and 18-month
old mice (bottom) were identified by anti-MAP2 immunoreactivity, and the
presynaptic calyceal terminal stained with vGluT1. Images have shared
orientation, with midline to the right, dorsal up. Scale bar is 100 μm
in both images. B. Neuronal cell size was evaluated as volume of
MAP2-positive signal in 9–15 μm thick confocal stacks, and is
significantly reduced at 18 months, relative to neurons in 1-month old MNTB.
C. Neuronal cell density was evaluated as the area occupied by
MAP2-positive signal within the MNTB nucleus, and was substantially reduced in
older mice.