Morphological and neurotransmitter phenotypes of dying cells in mice lacking VMAT2 at P3. At early stages of apoptosis, morphological characteristics can be recognized using activated caspase-3 (A–C) or caspase-9 immunoreactivity (A′–C′). A, A′, In layer V of the cerebral cortex, activation of caspase-3 (A) or caspase-9 was only observed in large pyramidal neurons. B, C, B′, C′, In the supragranular layers of the cingulate cortex, activation of caspase-3 (B, C) or caspase-9 (B′, C′) was observed only in pyramidal neurons. Arrows indicate the apical dendrite. In normal mice, immunoreactivity to the vesicular glutamate transporter type 1 (vglut1) or type 2 (vglut2) labels axon terminals. In mice lacking VMAT2, the normal VgluT1- or VgluT2-positive punctas were observed in axons terminals (D–G). However, abnormal cytoplasmic accumulations of VgluT1 (D, E) or VgluT2 (F, G) were observed in many neurons of the cingulate cortex of VMAT2 KO. In some cases, VgluT1 (E) or VgluT2 (F) immunoreactivity was densely packed around a small round-shaped nucleus, a hallmark of pyknosis. Arrows indicate these abnormal locations. Scale bars: A, A′, C, C′, 15 μm; B, B′, 25 μm; D, F, 80 μm; E, G, 25 μm.