Additional Supporting information may be found in the online version of this article.

DVDY_21781_sm_SupFigS1.tif1180KSupp. Fig. S1. Embryos treated at Hamburger and Hamilton stage (HH) 11 and examined at day 9. <B>A:</B> Side view of a normal embryo at day 9. <B>B:</B> Severe facial malformations are apparent at day 9 in embryos infected with RCAS-<I>Bmp-4</I>. The jaws are shortened. Scale bar = 2 mm.
DVDY_21781_sm_SupFigS2.tif2815KSupp. Fig. S2. Embryos treated at Hamburger and Hamilton stage (HH) 15 and examined at day 15. <B>A:</B> Side view of a normal embryo at day 15 illustrating the upper and lower jaws (UJ and LJ respectively). <B>B:</B> Treated embryos were extremely malformed. This embryo had a crossed beak. The lower jaw was pointing left while the upper jaw extending from the plane of the photograph. <B>C:</B> Alcian blue and Alizarin red staining demonstrated the extent of bone and cartilage formation by day 15. <B>D:</B> In treated embryos, the noninfected side appeared fairly normal and contained bones and cartilage. However, the infected side was comprised of cartilage nodules (red arrows) and little bone. The asymmetric formation of the skeletal elements likely deflected the growth of the lower jaw to create the crossbeak.
DVDY_21781_sm_SupFigS3.tif1345KSupp. Fig. S3. Time course of infection. <B>A–C:</B> Embryos infected at day 5 (A), day 6 (B), and day 7 (C) have a larger Meckel's cartilage. <B>D:</B> Embryos infected on day 8 appear normal. Scale bar = 5.0 mm.
DVDY_21781_sm_SupFigS4.tif4128KSupp. Fig. S4. Chondrocytes were hypertrophic at day 19. <B>A–C:</B> <I>Sox9</I> (A), <I>Col2</I> (B), and <I>Col10</I> (C) were expressed by chondrocytes at day 19, but <I>Sox9</I> and <I>Col2</I> appeared down-regulated compared with earlier time-points. Scale bar = 200 μm.

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