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Science  15 Oct 2010:
Vol. 330, Issue 6002, pp. 297
DOI: 10.1126/science.330.6002.297-a

When searching for a friend in a crowd, we look for characteristics such as height, hair color, and facial features. Young et al. have introduced facial variation experimentally in a quantitative analysis of the Sonic Hedgehog (SHH) signaling pathway in chickens. They varied SHH activation in the brains of avian embryos before the formation of the face. Microscopy and microcomputed tomography as well as gene expression and cell proliferation measurements revealed that variations in SHH activity from the forebrain resulted in variations in the shape of the upper jaw. Furthermore, mitotic activity in the growth zone of the midface correlated with facial shape. This work may be extended to understanding the phenotypes of SHH-associated diseases and facial malformations, including holoprosencephaly.

Development 137, 3405 (2010).

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