Notch and Hedgehog in specifying organ primordium

The avian thymus and parathyroid (T/PT) common primordium derives from the endoderm of the third and fourth pharyngeal pouches(3/4PP). The molecular mechanisms that govern T/PT development are not fully understood. Hélia Neves’ group at IMM/FMUL studied the effects of Notch and Hedgehog signaling modulation during common primordium development using in vitro, in vivo and in ovo approaches. Their results, published in an article by Figueiredo et al entitled “Notch and Hedgehog in the thymus/parathyroid common primordium: Crosstalk in organ formation”, show that impairment of Notch activity reduced thymus- and parathyroid-fated domains in the 3/4PP and compromised the development of the parathyroid glands and showed that it acts in a Hedgehog-dependent manner.