Fig. 1.

Transient Shh signaling inhibition causes cleft lip due to a deficiency of the medial nasal process. Representative mouse embryos exposed to vehicle (A-D) or cyclopamine (E-H) are shown at the indicated stages of development (n=3 embryos from two independent litters per stage per treatment). The medial nasal process (MNP) is outlined. Note the deficient frontonasal prominence (FNP)-derived MNP of a cyclopamine-exposed embryo at GD10.25 that precludes fusion with the maxillary process (MxP) at GD11.0, leading to unilateral (shown in H) or bilateral cleft lip visible at GD14.0. LNP, lateral nasal process. Scale bars: 300 μm.