Cover legend: Striatal neurons from embryonic day 17.5 Frizzled3 knock-out mice, stained for dopamineand cAMP-regulated phosphoprotein of 32 kDa (DARPP-32; green). The striatum is normally heavily innervated by meso-diencephalic axons at this developmental stage, but the neurons shown here still await innervation by these projections. For more information, see the article by Fenstermaker et al. in this issue (pages 16053–16064).