Expression of two-pore-domain channels in different regions of the hippocampus. Low-power dark-field images of emulsion-dipped coronal sections through the hippocampus.A–F show labeling for the six channel mRNAs through the rostral/dorsal hippocampus; this view corresponds to the film autoradiograms seen in Figure 1I. Note the differential distribution through the various pyramidal cell populations (CA1, CA2, andCA3), the approximate boundaries of which are marked byarrowheads. Also, there was TASK-3 labeling in scattered cells of the nonpyramidal layers (arrow inC); these are likely hippocampal interneurons.G and H illustrate differential TASK-3 expression in the ventral/caudal hippocampus compared with the rostral/dorsal expression illustrated above. G shows TASK-3 expression in the ventral/caudal dentate gyrus and corresponds to the ventral portion of the film autoradiogram in Figure1F. Note that there was particularly intense labeling of dentate gyrus granule cells in the ventral hippocampus but very little expression by these cells in the dorsal hippocampus (C). H shows TASK-3 expression in the ventral/caudal portion of CA3 and is taken from a section corresponding to the film autoradiogram seen in Figure1G. The CA3 pyramidal cell layer is marked bycurved arrows and traverses the entire panel. Note that there is much more TASK-3 expression in cells in thebottom (i.e., ventral) part of this panel when compared with cells in the top part of the panel and when compared with TASK-3 labeling in CA3 of the dorsal hippocampus (C). Scale bar, 500 μm.