a, Representative images of E13.5 wild-type and Ift88cKO ventricular zone surface stained for PCNT (green) and ARL13B (red), and with DAPI (blue) (n = 3). High-magnification images of individual centrosomes are shown in the insets. Note the complete loss of primary cilia in the Ift88cKO cortex by E13.5. Scale bars, 10 μm (main image); 1 μm (inset). b, Representative ssTEM images of E15.5 wild-type (top) and Ift88cKO (bottom) ventricular zone surface showing individual centrosomes of RGPs in the apical endfeet. High-magnification images (white dashed boxes) are shown on the right. Note that the Ift88cKO mother centriole possesses the DAPs that are anchored at the apical membrane (red arrows) and the sDAPs (yellow arrows), but does not support any microtubule-based ciliary axoneme (wild type, n = 9 centrosomes; Ift88cKO, n = 20 centrosomes). All wild-type mother centrioles were anchored to the apical membrane with microtubule-based cilia. All Ift88cKO mother centrioles were anchored to the apical membrane, but none possessed microtubule-based cilia. Scale bars, 800 nm (left); 200 nm (right). c, Representative images of E15.5 wild-type and Ift88cKO ventricular zone surface stained for PCNT (green) and CEP164 (red), and with DAPI (blue) (n = 3). High-magnification images of individual centrosomes are shown in the insets. Note the normal presence of CEP164 at the centrosome in the Ift88cKO cortex. Scale bars, 10 μm (main images); 0.5 μm (insets). d, Representative images of E15.5 wild-type (n = 6) and Ift88cKO (n = 6) ventricular zone surface stained for PCNT (green) and ODF2 (an sDAP marker; red), and with DAPI (blue). High-magnification images of individual centrosomes are shown in the insets. Note the normal presence of ODF2 at the centrosome in the Ift88cKO cortex. Scale bars, 5 μm (main image); 1 μm (inset). e, Representative whole-mount images of P21 wild-type and Ift88cKO brains. Scale bar, 0.5 cm. f, Quantification of the projected cortical area (n = 6 brains for each genotype). g, Images of P21 wild-type and Ift88cKO brain sections stained for CTIP2 (green) and CUX1 (red), and with DAPI (blue). Scale bar, 0.5 mm. h, Quantification of the cortical area (wild type, n = 4 brains; Ift88cKO, n = 4 brains). i, Images of the dorsal regions of P21 wild-type and Ift88cKO cortices stained for CTIP2 (green) and CUX1 (red), and with DAPI (blue). Scale bar, 100 μm. j, Quantification of the number of CUX1+ (left) and CTIP2+ (right) neurons per 250-μm column (n = 8 brains for each genotype). k, Representative images of P21 wild-type and Ift88cKO brain sections along the rostrocaudal axis, stained with DAPI (grey) (n = 5). Note that there is no obvious hydrocephalus in the Ift88cKO brain. Scale bar, 1 mm. A two-sided Mann–Whitney U test was used for statistical analysis. Bar charts show mean + s.e.m. Box plots as in Fig. 1.