Fig. 3

Pax9 expression in coronoid process of guinea pig and opossum. a, b, f Sirius red/alcian blue trichrome staining of parasagittal section through dentary of E32 guinea pig (a, b) and P10 opossum (f). The rudimentary coronoid process of the guinea pig is associated with a small temporalis muscle containing very few fibres (a, b) when compared with the large muscle surrounding the process of the opossum (f). c, g In situ hybridisation shows that Pax9 is expressed around the coronoid process of both the guinea pig (c) and the opossum (g). d, e. Immunofluorescence staining shows that Sox9 is weakly expressed around the coronoid process of the guinea pig (d) compared to the E15.5 mouse (e); temp temporalis muscle; cp coronoid process; Cdy mandibular condyle; Scale bar in a is 1000 µm; Scale in b–f is 100 µm