Fig 1L. ]PMID:15105372] Copyright: This image is from Cecconi F; Roth KA; Dolgov O; Munarriz E; Anokhin K; Gruss P; Salminen M, Development 2004; 131(9): 2125-2135 [doi:10.1242/dev.01082] and is displayed with the permission of The Company of Biologist Limited who owns the Copyright.