Figure 2.

Synaptic interaction between SpNs and MpNs is found just below the subplate layer. (A) Electron microscopic images of synapses on MpNs in the E16 cortical section. The areas indicated by the rectangles and circles are enlarged in the right. Synapse located in 1-a is enlarged as an inset. Scale bars, 50 μm for the left image, 200 nm for a, 10 μm for 1–4. (B) Hypothetical model for the interaction between SpNs and multipolar neurons. SpNs form transient glutamatergic synapses on multipolar neurons, which induce a Ca²⁺ influx in multipolar neurons through the NMDA receptor. Calcium signaling may alter gene expressions involved in cytoskeletal remodeling and cell adhesiveness, leading to multipolar-to-bipolar transition (Ohtaka-Maruyama et al., 2018).