Fig. 3.

Lmnb1^CS/CS embryos have smaller brains and exhibit a defect in layering of neurons in the cerebral cortex. (A–C) Photographs of wild-type, Lmnb1^CS/CS, Lmnb2^CS/CS, Lmnb1^+/−, and Lmnb1^−/− mice at E19– postnatal day (P)1. (Scale bars, 5 mm.) (D–F) Mouse brains viewed from the top at E19–P1. (Scale bars, 1 mm.) (G–I) H&E staining of coronal and sagittal brain sections at E19–P1. (Scale bars, 1 mm.) (J) Sizes of the cortex and midbrain in wild-type, Lmnb1^CS/CS (B1CS), and Lmnb2^CS/CS (B2CS) embryos (measured from the top of brains, see E). Lmnb1^+/+, n = 6; Lmnb1^CS/CS, n = 5; Lmnb2^+/+, n = 4; Lmnb2^CS/CS, n = 5. The midbrain was 21.5 ± 7.6% smaller in Lmnb1^CS/CS mice than in wild-type mice, P < 0.0001; the cortex was 9.1 ± 4.6% smaller in Lmnb1^CS/CS mice than in wild-type mice, P = 0.0072. Values represent mean ± SD (K) Immunofluorescence microscopy of the cerebral cortex of E19–P1 wild-type (WT, Lmnb1^+/+), Lmnb1^CS/CS (B1CS), Lmnb2^CS/CS (B2CS), Lmnb1^+/−, and Lmnb1^−/− embryos with antibodies against Cux1 (red) and Ctip2 (green). The layering of cortical neurons in Lmnb1^−/− embryos was abnormal, as reported previously (24). Lmnb1^CS/CS mice also exhibited a cortical layering defect, but it was milder than in Lmnb1^−/− mice. No abnormalities were detected in Lmnb1^+/− mice. (Scale bars, 100 µm.)