Skip to main content
. Author manuscript; available in PMC: 2017 Aug 17.
Published in final edited form as: Wiley Interdiscip Rev Dev Biol. 2011 Dec 27;1(2):253–266. doi: 10.1002/wdev.25

Figure 6. Models for Hox gene regulation.

Figure 6

Left, gradient model. As the embryo extends, the concentration of a secreted factor decreases, which provides a signal for the expression of more posterior Hox genes. It is also possible that a signal increases as the embryo extends. Right, Chromatin model. As the embryo extends, the chromatin opens up progressively in a 3′ to 5′ direction, allowing more posterior Hox genes to be expressed.