Fig. 1. lacZ knock-in into the Dlx3 locus and Dlx3 expression pattern. (A) Exon-intron organization and enzyme restriction patterns of murine Dlx3 locus (N, NdeI and E, EcoRI), before and after homologous recombination (upper panel). Genotyping by Southern blot (lower panel, left) and PCR (lower panel, right) of wild type (WT) and lacZ knock-in (+/-; Dlx3^Kin/+) mice. White and black arrowheads indicate the localization of the oligonucleotides used in the PCR reactions. (B) Whole-mount X-gal staining shows Dlx3/lacZ expression patterns in the Dlx3^Kin/+ mice. (i) Clarified head of embryological stage, E15.5 Dlx3^Kin/+ embryo by benzyl-benzoate/benzyl alcohol after X-gal staining showing expression in the vibrissae; (ii) cross and (iii) sagittal sections of vibrissae at E16.5. (iv) Dlx3/lacZ expression in hfs in the epidermis of E16.5 head (arrows) and (v) sagittal section through the head, showing expression in the intramembranous bone of the cranium (arrowheads) and the hf (arrows).