Differential distribution of PC molecular species in sagittal mouse brain sections. MALDI-IMS spectra of a brain section simultaneously identified the heterogeneous distributions of several PCs. Schema of the mouse brain sagittal section and ion images of PCs obtained by IMS are shown. Ion images of PCs are arranged according to their fatty acid (FA) composition. PCs with identical FA compositions at the sn-1 position are arranged lengthwise, whereas those with identical FA compositions at the sn-2 position are arranged sideways. The structures of PCs are also presented. Among the PCs, AA-PCs showed characteristic localization in the hippocampal cell layers (arrowheads). Among DHA-containing species, two abundant species, PC (diacyl-16:0/22:6) and PC (diacyl-18:1/22:6), were commonly enriched in the granule layer of the cerebellum, whereas PC (diacyl-18:0/22:6) showed a characteristic dotted distribution pattern near the cell layer (arrows). CBX, cerebellar cortex; CP, corpus striatum; CTX, cerebral cortex; HPF, hippocampal formation; TH, thalamus.