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The spatial distributions of various specific lipids in freeze-dried mouse brain sections were monitored using time-of-flight secondary ion mass spectrometry (TOF-SIMS). Mouse brain sections were prepared by cryosectioning, rinsing in 0.15 M NH₃HCOO, and freeze-drying, after which the samples were analyzed directly by TOF-SIMS, using Au₃⁺ ions as primary ions. Positive and negative TOF-SIMS spectra of the tissue surface contained peaks from quasimolecular ions of a variety of specific lipids, including cholesterol, sulfatides, phosphatidylinositols, and phosphatidylcholines. Images showing the spatial signal intensity distributions of specific ions were recorded across analysis areas ranging from 100 × 100 μm² to 9 × 9 mm². The results demonstrate a highly complementary localization of cholesterol and phosphatidylcholine over dimensions from millimeter to micrometer range. Characteristic spatial …