Figure 6.

Axon growth and glutamatergic synaptogenesis in Neurod2/6 double mutants. A, Lucifer-yellow-filled projection neurons in upper layers of cortical slices prepared from control and Neurod2/6 double-mutant mice at E18. Axons are marked by arrowheads. B, Fluorescent staining for F-actin (red) combined with immunostaining for the neuronal marker HuC/D in cortical cell cultures prepared from P1 mice at 7 DIV. C, D, Reduced expression levels of presynaptic and postsynaptic components of glutamatergic synapses in the neocortex of adult double mutants. Immunostaining for Vglut1 (C) and NR1 (D) on coronal brain sections at 2 months of age. E, Immunostaining for axon bundles (Gap43; green) and nuclei (DAPI; blue) in cortical cell cultures from P1 mice after 28 DIV. F, Spontaneous excitatory synaptic activity in cortical cell cultures from control and double-mutant mice after 21–28 DIV by patch-clamp recording. Left, Spontaneous burst activity was recorded at ∼10-fold higher frequency in control cultures (15 bursts/3 min; n = 20 cells) than in double-mutant cultures (<1 burst/3 min; n = 14 cells). Middle and right, The frequency of background sEPSC was strongly reduced in double-mutant cultures compared with controls. Str, Striatum. **p < 0.01 and ***p < 0.001.