Figure 1.
MGL localization in the developing nervous system. A–A2, MGL+ olfactory (A1, arrows) and thalamic axons (A2, arrows), ventricular zone progenitors (open arrowheads), and precursor cells populating the striatal differentiation zone (sdz) are present by E12.5. B, B1, Semiquantitative assessment of MGL distribution in postmitotic neurons of cerebral subfields. Incrementing horizontal line width correlates with increasing signal intensity. C–C3, Sagittal section across the brain and upper body segment of a homozygous tau–EGFP+ embryo photographed at E14.5 reveals MGL+ axons in the trigeminal ganglion (5Gn), submandibular trigeminal nerves (5man), and spinal trigeminal tract (sp5; C2), optic stalk (os), parabrachial/microcellular tegmental nuclei (PB/MiTg; C3), and thalamocortical (arrowheads) and olfactory tracts (1n). Open arrowheads indicate MGL+ subventricular zone progenitors. D–D4, MGL+ TCAs course in the inferior thalamic radiation (D1) before invading the cortical subplate (D2, arrows). D1, MGL+ axons at the anterodorsal thalamic boundary are intermingled with GABAergic neurons. D2, Radially migrating cortical neurons, presumed pyramidal cells, also express MGL. Note that GFP+ GABAergic interneurons are MGL− at this developmental stage. D3, Brn-1+/tau–EGFP+ pyramidal cells (arrowheads) migrate through the MGL+ subplate to reach their final positions. D4, MGL+ puncta are in close apposition to tau–EGFP+ cortical neurons (arrowheads). E–E2, MGL+ axons populate the cortical IZ, hippocampal fimbria (f), lateral olfactory tract (lot), and optic nerves (och) by E16.5. Note that the striatal neuroepithelium (ne) lacks appreciable MGL expression. F, F1, By E18.5, MGL becomes restricted to neuronal perikarya and disappears from long-range axons. G, Increased [2-AG] coincides with MGL redistribution by birth. *p < 0.05 versus E14.5–E18.5 (Student's t test). Open rectangles denote the location of insets. Abbreviations used in all figures are listed in the supplemental information (available at www.jneurosci.org as supplemental material). Scale bars: A, A2, C–C2, D, E, F, 100 μm; A1, D1–D3, 25 μm; D4, E1, E2, F1, 10 μm.