Fig. 1.

The onset of apoptosis occurs earlier in the MKO embryo than the BKO embryo. Representative photomicrographs of active Caspase-3 (AC3) immunohistochemistry labeling of apoptotic cell death in horizontal spinal cord sections at (a) E10, (b) E11, and (c) E13 from CTL, MKO, and BKO embryos. a In MKO embryos, apoptosis appears first in the ventral spinal cord at E10 whereas no apoptosis is observed in the BKO spinal cord. b By E11, apoptosis is predominantly in the dorsal spinal cord of the MKO embryo. Apoptosis begins at E11 in BKO embryos and similar to the MKO embryo, it is first observed within the ventral spinal cord. c By E13, apoptosis is only located in the dorsal spinal cord in the MKO embryo and in the BKO embryo, apoptosis has spread across the ventral and into dorsal spinal cord. D dorsal, V ventral. Scale bar = 200 μm (a–c)