Hindbrain patterning revisited: timing and effects of retinoic acid signalling.
Retinoids play a critical role in patterning, segmentation, and neurogenesis of the posterior hindbrain and it has been proposed that they act as a posteriorising signal during hindbrain development. Until now, direct evidence that endogenous retinoid signalling acts through a gradient to specify cell fates along the anteroposterior axis has been missing. Two recent studies tested the requirement for retinoid signalling in the developing hindbrain through systematic application of a pan-retinoic acid receptor antagonist. They demonstrate a stage-dependent requirement for increasing retinoid signalling activity along the hindbrain that proceeds from anterior to posterior. Together these findings challenge the concept of a stable gradient of retinoic acid across the hindbrain and warrant a re-interpretation of the phenotypes obtained by genetic and nutritional disruption of retinoid signalling in the amniote embryo.
Begemann
G
G
Department of Biology, University of Konstanz, Germany. gerrit.begemann@uni-konstanz.de
Meyer
A
A
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D012249:Rhombencephalon / Q000196:embryology*; D015398:Signal Transduction / Q000502:physiology*; D019170:Somites / Q000378:metabolism; D013997:Time Factors; D014212:Tretinoin / Q000378:metabolism*
D014212:Tretinoin