Fig. 1. Analysis of mandible structure in Ednra^–/– embryos. E18.5 wild-type (Ednra^+/+; A,C,E,G,I) and Ednra^–/– (B,D,F,H,J) embryos. (A,B) Unlike wild-type embryos (A), the lower jaw of an Ednra^–/– embryo is shortened and is covered by vibrissae (asterisks in inset in B denote follicles; arrows denote actual vibrissae) (B). (C-J) Alizarin Red and Alcian Blue staining to visualize bone and cartilage structures, respectively. (C,D) In a lateral view, the mandible in Ednra^–/– embryos appears shortened and flattened (D) compared with that of the wild-type embryo (C). This bone, the pseudo-maxilla (mx*) is aberrantly connected to the jugal bone (j) through a bone resembling a duplicated jugal (j*). Incisors (i) of Ednra^–/– embryos are present (inset in D) but are set primarily in mesenchyme. (E,F) A ventral view shows bilateral foramina in the pseudo-maxilla of Ednra^–/– embryos (F) as well as the presence of incisors (insets). (G,H) Removal of other structures emphasizes the mirror image appearance of the pseudo-maxilla and pseudo-jugal bones in Ednra^–/– embryos (H). (I,J) A frontal view of the pseudo-maxilla shown in H shows pseudo-palatine bones (pl*) attached to the pseudo-maxilla in Ednra^–/– embryos (J). (K,L) Two views of the alisphenoid bone in wild-type (Ednra^+/+;bottom) and Ednra^–/– (top) embryos. Both the ala temporalis (at) and lamina obturans (lo) regions of the alisphenoid appear to be duplicated in Ednra^–/– embryos. at*, duplicated ala temporalis; bs, basisphenoid; lo*, duplicated lamina obturans; h, hyoid.