Fig. 2. Disrupted cortical neuronal placement in ₃ integrin-deficient mice. 3 integrin-deficient mice were crossed with Thy1-GFP line-I (Feng et al., 2000), known to express GFP in layer VI neurons (A). At P0 (B), GFP expression is limited to distinct medial and lateral domains of the occipital region of the cortex. Expression of GFP was also noticed in the striatal area and in an area surrounding third ventricle (B). In wild-type lateral occipital cortex at P0 (C), layer VI neurons express GFP, whereas in 3 integrin-deficient cortex (D), GFP-positive neurons were ectopically placed, away from their destination in layer VI. Higher magnification images of GFP-labeled neurons in wild-type (C', arrowheads) and 3 integrin mutant (D', arrows) cortex show disrupted apical dendrite orientation in 3 integrin neurons. Immunolabeling with anti-calretinin or calbindin antibodies indicates malpositioning of cortical interneurons in 3 integrin mutants. In P0 wild-type cortex, anti-calretinin (E) or calbindin (G) antibodies primarily label bands of neurons in newly formed layers I-III and III/IV, respectively. By contrast, calretinin-(F) or calbindin (H)-expressing neurons are diffusely distributed in 3 integrin mutant cortex. OC, occipital cortex; ST, striatum; 3rd V, third ventricle; LV, lateral ventricle; CP, cortical plate; SP, subplate; IZ, intermediate zone; VZ, ventricular zone; WM, white matter. Scale bar: 100 µm in A; 75 µm in C,D; 60 µm in C',D'; 180 µm in E-H.