Conditional deletion of both mcl-1 and bcl-x—a double conditional knockout (DKO) results in complete loss of the CNS by E14. a Photomicrographs of representative cresyl violet-stained sagittal sections of E14 CTL, MKO, BKO, and DKO embryos. Representative higher magnification photomicrographs of cresyl violet stained sections of (b) cortex and (c) spinal cords for each genotype. Scale bars = 2000 μm (a), 100 μm (b, c)