The mode of development of an inherited form of anencephaly in the house mouse.

Anencephaly in the xn strain of mouse is a condition determined by a single autosomal recessive gene. At birth, affected animals bear a cap of degenerate cerebral tissue devoid of bony covering. The early development of this malformation was studied in embryo mice from the stage of neural groove formation until after the neural tube has normally closed. The abnormal embryos could be recognized before the anterior neuropore had completely closed in normal litter mates. Detection of the cerebral malformation at this early stage of gestation suggests that the inherited murine anencephaly is due to primary failure of the neural tube to close.