How is pattern formation achieved during thymus development?

Understanding pattern formation is a fundamental problem in developmental biology. The thymus and parathyroid organs are critical components of our immune and endocrine systems, respectively. Yet, despite their very different adult functions, the two organs originate from a common embryonic primordium. We know that there are two opposing signaling gradients, SHH and BMP4, in the primordium. It would be interesting to examine how these organs arise under the action of these and other developmental regulators.
Qiaozhi Wei, Brian G Condie PLoS ONE: 2011, 6(11);e26795