Roles for Laminin in Embryogenesis: Exencephaly, Syndactyly, and Placentopathy in Mice Lacking the Laminin α5 Chain

Here, we show that the laminin α5 chain is required during embryogenesis. The α5 chain is present in virtually all BLs of early somite stage embryos and then becomes restricted to specific BLs as development proceeds. BLs that lose α5 retain or acquire other α chains. Embryos lacking laminin α5 die late in embryogenesis. They exhibit multiple developmental defects, including failure of anterior neural tube closure. In addition to exencephaly, syndactyly, and placentopathy, several defects were seen in internal organs of Lama5 −/− embryos, including small or absent kidneys. Some of these defects were variable in severity and penetrance, but all can be associated with BLs that normally contain laminin α5.