<i>Col3a1^−/−</i> mice have cortical abnormalities.

<p>Sagittal sections from one <i>Col3a1^+/+</i> (<b>A</b>) and three <i>Col3a1</i>^−/− forebrains (<b>B–I</b>) stained with Nissl. In contrast to the well-developed cortex in <i>Col3a1^+/+</i> brains (A), cortical malformation was seen in <i>Col3a1</i>^−/− brains, characterized by the presence of ectopic clusters of neurons migrating into the marginal zone and disrupting the lamination of the cortex (B–I, arrowheads). Scale bar, 200 µm.