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. 2010 Feb 9;107(11):5076–5081. doi: 10.1073/pnas.0908790107

Fig. 3.

Fig. 3.

Lmnb2 deficiency causes defective neuronal migration in the brain. (A) Birthdating experiment demonstrating defective neuronal migration in the cortex of Lmnb2−/− embryos. Pregnant females were injected with BrdU at E13.5; brains were collected at E18.5, sectioned, and stained with DAPI and a rat monoclonal antibody against BrdU. Neurons born at E13.5, the time of the BrdU injection, stain very intensely for BrdU and were present within the lower levels of the cortical plate in WT mice. Neurons born later (therefore containing less BrdU) migrate to more superficial layers of the cortex. In Lmnb2−/− embryos, intense BrdU staining is noted in the most superficial layers of the cortical plate, consistent with an inability of the neurons born later to migrate past older BrdU-positive neurons. Arrow indicates the orientation of neuronal migration. (B) Sections from the same experiment stained with a sheep polyclonal antibody against BrdU (red) and a rat monoclonal against Ctip2, a marker for cortical layers V and VI (green). In WT embryos, neurons with the strongest BrdU staining were found in deep layers of the cortical plate together with Ctip2 staining. In contrast, in the Lmnb2−/− embryos, BrdU-positive and Ctip2-positive cells were both found in the more superficial part of the cortex. (C) Immunostaining of cortical sections of E19.5 WT and Lmnb2−/− embryos with antibodies against Ctip2 (green) and NeuN (red). In WT brains, a large number of mature neurons positive for NeuN were detected above layers V and VI (positive for Ctip2), whereas in Lmnb2−/− brains, many NeuN-positive cells were found below Ctip2-positive cells. (D) Immunostaining of cortical sections of E19.5 WT and Lmnb2−/− embryos with antibodies specific for Ctip2 (green) and FoxP1, a marker for layers III–V (red). In Lmnb2−/− embryos, FoxP1-positive neurons accumulated in lower levels of the cortex. (E) Immunostaining of cortical sections of E19.5 WT and Lmnb2−/− embryos with antibodies against Cux1, a marker for layers II–IV (green) and FoxP1 (red). In WT brains, Cux1-positive neurons were mainly located above the cells that stain for FoxP1, whereas in Lmnb2−/− brains, many Cux1-positive cells were located below FoxP1-positive cells. (F) Immunostaining of cortical sections of E19.5 WT and Lmnb2−/− embryos with antibodies specific for FoxP2, a marker for layer VI (green), and for Ctip2 (red). In WT embryos, Ctip2 staining was detected in the upper part of the FoxP2 territory, corresponding to layer V, whereas in Lmnb2−/− embryos the two cell populations were intermixed.