All Phenotypes Nkx2-5<tm1.1Gum> MGI Mouse

abnormal pyloric sphincter morphology ( J:228275 )

• embryos treated with tamoxifen at E16.5 show a pyloric sphincter constriction that is 33% wider than that in wild-type controls at E18.5

• however, positioning of the epithelial pyloric border is normal at E18.5

abnormal stomach smooth muscle circular layer morphology ( J:228275 )

• embryos treated with tamoxifen at E14.5 show an altered shape of the dorsal inner circular muscle (ICM) at E16.5

abnormal stomach smooth muscle outer longitudinal layer morphology ( J:228275 )

• embryos treated with tamoxifen at E14.5 show a nearly complete absence of the alpha-smooth muscle actin (alpha-SMA)-positive dorsal pyloric outer longitudinal muscle (OLM) at E16.5, suggesting impaired maturation of the pyloric OLM fascicle

• embryos treated with tamoxifen at E16.5 (when OLM is already formed and strongly alpha-SMA-positive) show severe attenuation or regression of the dorsal pyloric OLM by E18.5

• remaining cells appear loosely organized and only weakly alpha-SMA positive

increased apoptosis ( J:228275 )

• embryos treated with tamoxifen at E14.5 show a ~2-fold increase in the proportion of caspase 3-positive cells within the pyloric OLM at E16.5 relative to wild-type controls

• however, no significant changes in apoptosis are detected within the ICM

decreased cell proliferation ( J:228275 )

• embryos treated with tamoxifen at E14.5 show a 25% decrease in the proportion of BrdU-positive cells in the pyloric OLM fascicle at E16.5 relative to wild-type controls

• however, no significant changes in proliferation are detected within the inner circular muscle (ICM)