Ruga 7 in hamster is equivalent to ruga 8 in mouse and also coincides with A/P Shox2 / Meox2 expression boundary. (A) Ruga pattern and numbering in the hamster Mesocricetus auratus. (B) Sequence of hamster ruga appearance as followed with Ma-Shh probe. Embryos were ranked according to their weight. (C) Drawings of mouse and hamster palate showing that the boundary ruga is found more anteriorly in the hamster by comparison to the mouse. Drawings were made from pictures shown in Fig. 1A and 6A. Scale was adapted for comparison. (D) Whole mount in situ hybridization of hamster embryonic upper jaws (weight class: 170–180 mg) with Ma-Shh, Shox2 and Ma-Meox2 probes. (E) Sections of hamster embryonic upper jaws following whole mount hybridization with Ma-Shh (weight class: 170–180 mg), Shox2 and Ma-Meox2 (weight class: 160–170 mg) probes.