Fig. 4. Detection and purification of lacZ⁺ cells by fluorescence-activated cell sorting. Single cell suspensions of heterozygous embryos at E12.5 were stained with the fluorescent lacZ substrate FDG and cell death was detected by adding propidium iodide (PI). In FACS analysis, only vital cells in gate R1 (FSC/SSC) were considered for data analysis (A). Cells from wild-type embryos were used as control and almost no events were detected in gate R2 (B). About 3% of the heterozygous cells analyzed, represent vital Anxa5-lacZ⁺ cells (C). Similar amounts of Anxa5-lacZ⁺ cells were detected in embryos at E8.5 (D) and E10.5 (E) as well as in adult brain meninges (F). The percentages of cells within the gate are depicted, genotypes (wild type, wt; heterozygous, +/–) are indicated.