Neural tube and body wall defects in AP-2 chimeric mice. (A) Newborn AP-2-null mouse. mn, mandible; t, tongue; h, heart; lv, liver. (B) E13.5 chimeric mouse with similar defects to AP-2-null animal. The lacZ gene present in one of the disrupted AP-2 alleles enables a component of the AP-2-null ES cell contribution to be detected by β-gal activity. (C and D) Failure of body wall closure in E18.5 AP-2 chimeric mice. In D, the schisis extends behind the ear pinna. (E) Transition of body wall at the lateral margins of an AP-2-null newborn pup from multilayered epidermis to thin peridermal covering. (F and G) E18.5 chimeras exhibiting cranial neural tube closure defects.