Fig. 6. Fate mapping of Pitx2 daughters in craniofacial development. (A,B) 11.5 dpc abc^cre+/– (A) and abc^cre ;abc^null (B) embryos hybridized to cre. Cre expression is restricted to oral ectoderm and is not found in the facial ectoderm (asterisk). (C-E) Sections of 11.5 dpc embryos hybridized to cre. Coronal (C,D) and parasagittal sections (E) show restricted expression of cre in oral ectoderm (arrows). Boxed area in C corresponds to higher-power image in D. (F,G) abc^cre+/– (F), abc^cre ;abc^null (G) rosa26 reporter^+/– 11.5 dpc embryos. (H,I) Ventral view of abc^cre+/– rosa26 reporter compound heterozygous 11.5 dpc embryos stained for lacZ (H) showing lacZ-positive Pitx2 daughter cells (arrowhead). (J,K) Lateral view of abc^cre+/– (J) and abc^cre ;abc^null (K) rosa26 reporter^+/– 11.5 dpc embryos stained for lacZ. Arrowhead (J) indicates lacZ-positive Pitx2 daughter cells and arrow (K) denotes cells that move ectopically. (L-O) Oral view of floor of mouth (L,M) or roof of mouth (N,O) from abc^cre+/– (L,N) and abc^cre ;abc^null (M,O) rosa26 reporter ^+/– 11.5 dpc embryos showing migrating Pitx2 daughter cells (arrows). (P-S) Parasagittal sections of 10.5 dpc (P,Q) and 12.5 dpc (R,S) abc^cre+/– (P,R) and abc^cre ;abc^null (Q,S) rosa26 reporter^+/– embryos. Arrowheads indicate lacZ-positive Pitx2 daughter cells contributing to oral cavity roof and asterisk indicates region that has diminished contribution in Pitx2 mutant. Arrows indicate Pitx2 daughters contributing to mandibular oral and dental epithelium. e, eye; g, gut; fn, frontonasal process; lb, limb bud; md, mandible; mx, maxilla; nc, nasal cartilage; nt, neural tube; oe, oral ectoderm; rp, Rathke's pouch; to, tongue.