GAD1 and hydrops fetalis: Lastly, we noticed an additional striking difference in the developmental profiles of the densities of EGFP-expressing Cajal–Retzius cells (at P7: 17.33 ± 0.58, P14:12.27 ± 0.96, P30: 8.64 ± 0.91, P60: 6.74 ± 0.50; in cells per 100 μm of HF; see also Table 2) versus GAD67-labeled interneurons (at P7: 7.61 ± 0.31, P14:9.89 ± 053, P30: 7.34 ± 0.64, P60: 8.052 ± 0.52; in cells per 100 μm of HF, p < 0.001).