Remarkably, while investigating the pathogenic mechanism of microcephaly due to mutation of the gene encoding PALS1 (protein associated with LIN7, also known as MPP5), a component of the CRB apical polarity complex, with either of two Cre drivers (hGFAP-Cre, or Emx1-Cre), we identified nuclei enclosed by cell membranes inside cells at the ventricular surface of the developing cortex (Fig. 1a, b, Supplementary Fig. 1, Supplementary Movie 1)28,29. Here, PALS1 is linked to microcephaly.