Pou3f4-Mediated Regulation of Ephrin-B2 Controls Temporal Bone Development in the Mouse
Figure 5
Comparative gene and Cre-mediated reporter expression in the developing middle ear at E12.5.
(A, B) Efnb2 and Pou3f4 gene expression domains, as shown in adjacent transverse sections through a wild-type E12.5 embryo. The stapedial artery, positioned roughly at the center of the stapes condensation, is marked by brown dots and by strong expression of Efnb2 in the arterial endothelium (A). Asterisks highlight the facial nerve dorsal to the stapes condensation. Arrowheads highlight a region of overlapping Efnb2 and Pou3f4 signal dorsal to the stapedial artery and surrounding the facial nerve. (C, D) Transverse section through a wild-type E12.5 embryo stained with alcian blue/nuclear fast red (C) and a scaled schematic drawing (D) of the stapes condensation and neighboring structures. White dot in (C) highlights the stapedial artery. Asterisks in (C,D) highlight the VIIth nerve. cc, otic capsule condensation; cv., cardinal vein; oe, otic epithelium; ph./eu., nascent pharynx/eustachian tube; pom, periotic mesenchyme; sta, stapes mesenchymal condensation; st art., stapedial artery; sty, styloid process mesenchymal condensation; vii n., VIIth nerve. (E, F) Sox9-IRES-Cre- (E) and Pou3f4-Cre- (F) mediated ROSA-YFP reporter expression in the region of the E12.5 nascent middle ear, as schematized in (D). (C–F) are shown to scale. Cre-positive cells or descendents of Cre-positive cells are labeled green. DAPI-positive nuclei are purple. White dots highlight the stapedial artery; asterisks highlight the VIIth nerve.