FIG. 4.

Chrna7:Cre ablated embryo defects. A: Staining (H&E) of an E15.5 embryo shows the spina bifida defect (double arrows) and omphalocele with extruded liver (OMPH). The proposed overgrowth of the normal liver is seen in the extruded portion of this organ (arrow). B: The placenta (p) develops normally (E13.5), although some necrotic conceptuses are regularly observed (not shown). Note that the ventral body wall defect is already visible (arrowhead) as is the spina bifida defect (arrow). C: At E16.5, Chrna7:Cre ablated embryos frequently manifest myelomeningocele (i.e., extrusion of the meninges and spinal cord) at the site of the SB (double arrows) and nerve roots (arrow). The abnormal tail (t) is also present. D: A section through the same embryo stained with antibodies to neural marker peripherin. This highlights the dorsal root ganglia (DRG) and shows the extruded nerve root from one of these (arrow) that is topographically displaced. E: Pelvic anatomy of an E16.5 Chrna7:Cre ablated fetus. The SB defect and extruded DRG nerve root is identified (double arrows). In these embryos, the urogenital system (asterisk) and anus (arrow) appear unaffected as does the axial autopod skeleton (stacked arrowheads). Notable is the hernia sac and peritoneum membrane surrounding the extruded abdominal organs (arrow heads) that define the omphalocele. This fragile membrane is frequently disrupted during dissection. All scale bars are 1 mm.