Fig. 4.

Abnormal morphology in the upper nasal region in Pkr2^−/− mice at E12.5 and E13.5. HE-stained parasagittal sections of the upper nasal region in wild-type littermates at E12.5 (A, E, and I), Pkr2^−/− mice at E12.5 (B, F, and J), wild-type littermates at E13.5 (C, G, and K) and Pkr2^−/− mice at E13.5 (D, H, and L). Note that a sphere-shaped structure was observed at the region between the olfactory pit and forebrain in Pkr2^−/− mice at both E12.5 and E13.5 (arrowhead in B and D). This structure is particularly evident when viewed at higher magnification (arrowhead in F, H, J, and L). OP, olfactory pit, F, forebrain. [Scale bars, 200 μm (A–D), 100 μm (E–H), and 50 μm (I–L).]