Fig. 1.

dI1i neurons are absent in the lateral deep dorsal horn of the Barhl2-null spinal cord. (A) X-Gal histochemistry on whole-mount embryos. At E11.5, Barhl2-lacZ⁺ dI1 neurons in Barhl2^lacZ/+ controls and Barhl2^lacZ/lacZ-null spinal cords are similarly distributed in one column. At E12.5, there are two lacZ⁺ columns in the controls; in contrast, Barhl2-nulls only have one column medially (yellow brackets). (B) X-Gal histochemistry on transverse cervical spinal cord sections. Between E11.5 and E13.5, control dI1 neurons migrate to the deep dorsal horn and resolve into the lateral dI1i (black arrowheads) and medial dI1c subtypes. In contrast, Barhl2-null dI1 neurons overwhelmingly migrate to and settle in the medial deep dorsal horn starting from E11.75. The lateral dI1i subtype is absent (red arrowheads). (Scale bars: A, 1 mm; B, 100 μm.)