File:Limb bud geometry and patterning.jpg

Geometry and Patterning of the Limb Bud

A Geometry of the limb bud.

• Yellow - ectodermal layer.
• Blue - dorsal.
• Green - ventral mesenchyme.
• Red line - indicates the dorsoventral boundary (solid - posterior, dashed - anterior).
• Thick grey lines - represent the flank, with the dots indicating the points of cross-section between the posterior and the dorsal view.

B Expression domains of patterning signals.

Legend

• AER - apical ectodermal ridge, expresses FGF encoding genes (Fgf8, Fgf4, Fgf9, Fgf17).
• ZPA - zone of polarizing activity, is the source of Sonic Hedgehog (Shh). Bone morphogenetic protein (BMP4) is expressed in a broad domain, which is progressively restricted in time. Gremlin1 is a BMP antagonist. BMP, Gremlin, Shh, and FGF are interlinked in signaling feedback loops, which causes their domains of expression and activity to change over time. Wnt5a is expressed in a proximo-distal gradient, with highest levels at the tip of the limb bud.

Links: Limb Development | Limb Abnormalities | Nature - Fgf8 morphogen gradient

Original file name: Figure 2. Pbio.1000421.g002.jpg

Reference

<pubmed>20644713</pubmed>| PMC2903596 | PLoS

Citation: Kicheva A, Briscoe J (2010) Limbs Made to Measure. PLoS Biol 8(7): e1000421. doi:10.1371/journal.pbio.1000421

Published: July 13, 2010

Copyright: © 2010 Kicheva, Briscoe. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.