FIGURE 20.

Determination of the border between lateral and caudal ganglionic eminence (LGE and CGE). The diagrams in the insets in (a) and (b) show the locations of the sections displayed in (a) and (b, c), respectively. In general, LGE shows much stronger expression of ERBB4 than CGE at both PCW 15 (a) and 21 (b, c). However, the border is not clear‐cut since the expression displays clear gradient. The transition zone between the LGE and CGE is identified between the solid and dashed lines based on the expression of ERBB4 (a, c) and CALB2 (much stronger in CGE than in LGE; see Figure 14b). In this study, the LGE‐CGE border is placed at the solid lines (a, c) to be conservative for the CGE. Note the ERBB4 expression in the red nucleus (RN in a), substantia nigra (SN in a, b), and ventral tegmental area (VTA in a) of the midbrain, and in the reticular thalamic nucleus (R), subthalamic nucleus (STH), and zona incerta (ZI) of the thalamus (b). ERBB4 is also expressed in the marginal zone (MZ) and ventricular‐subventricular zone (VZ‐SZ or VZ‐SZi) of the cortex (a‐c). Scale bar: 400 μm in (a) for (a‐c)